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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Mar. 12, 2018	Jun. 30, 2017
Document and Entity Information
Entity Registrant Name	AXCELIS TECHNOLOGIES INC
Entity Central Index Key	0001113232
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 644,303,947
Entity Common Stock, Shares Outstanding		32,128,818
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Product	$ 387,124	$ 244,295	$ 278,875
Services	23,437	22,685	22,620
Total revenue	410,561	266,980	301,495
Cost of revenue:
Product	234,932	149,007	181,060
Services	25,382	18,375	18,729
Total cost of revenue	260,314	167,382	199,789
Gross profit	150,247	99,598	101,706
Operating expenses:
Research and development	43,071	34,402	32,586
Sales and marketing	28,532	23,839	23,325
General and administrative	30,802	24,452	25,059
Restructuring charges		282	18
Total operating expenses	102,405	82,975	80,988
Income from operations	47,842	16,623	20,718
Other (expense) income:
Interest income	714	238	64
Interest expense	(5,121)	(5,073)	(4,976)
Other, net	396	(764)	(601)
Total other expense	(4,011)	(5,599)	(5,513)
Income before income taxes	43,831	11,024	15,205
Income tax (benefit) provision	(83,128)	23	527
Net income	$ 126,959	$ 11,001	$ 14,678
Net income per share:
Basic (in dollars per share)	$ 4.11	$ 0.38	$ 0.51
Diluted (in dollars per share)	$ 3.80	$ 0.36	$ 0.49
Shares used in computing net income per share:
Basic weighted average common shares	30,866	29,195	28,595
Diluted weighted average common shares	33,436	30,947	30,229

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Comprehensive Income
Net income	$ 126,959	$ 11,001	$ 14,678
Other comprehensive income:
Foreign currency translation adjustments	4,347	(847)	(2,664)
Amortization of actuarial gains and other adjustments from pension plan	108	(1)	(43)
Total other comprehensive income (loss)	4,455	(848)	(2,707)
Comprehensive income	$ 131,414	$ 10,153	$ 11,971

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 133,407	$ 70,791
Short-term restricted cash	750
Accounts receivable, net	75,302	50,573
Inventories, net	120,544	113,853
Prepaid expenses and other current assets	9,772	5,512
Total current assets	339,775	240,729
Property, plant and equipment, net	36,168	30,840
Long-term restricted cash	6,723	6,864
Deferred income taxes	83,148	1,060
Other assets	22,404	22,738
Total assets	488,218	302,231
Current liabilities:
Accounts payable	32,642	24,996
Accrued compensation	20,955	5,142
Warranty	4,112	2,426
Income taxes	273	240
Deferred revenue	16,181	10,335
Other current liabilities	5,124	4,592
Total current liabilities	79,287	47,731
Sale leaseback obligation	47,714	47,586
Long-term deferred revenue	1,964	674
Other long-term liabilities	5,643	4,785
Total liabilities	134,608	100,776
Commitments and contingencies (Note 14)
Stockholders' equity:
Common stock, $0.001 par value, 75,000 shares authorized; 32,048 shares issued and outstanding at December 31, 2017; 29,518 shares issued and outstanding at December 31, 2016	32	30
Additional paid-in capital	556,147	535,408
Accumulated deficit	(204,745)	(331,704)
Accumulated other comprehensive income (loss)	2,176	(2,279)
Total stockholders' equity	353,610	201,455
Total liabilities and stockholders' equity	$ 488,218	$ 302,231

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheets
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	75,000	75,000
Common stock, shares issued	32,048	29,518
Common stock, shares outstanding	32,048	29,518

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Total
Balance at Dec. 31, 2014	$ 28	$ 519,153	$ (1,218)	$ (357,383)	$ 1,276	$ 161,856
Balance (in shares) at Dec. 31, 2014	28,213
Increase (Decrease) in Stockholders' Equity
Net income				14,678		14,678
Foreign currency translation adjustments					(2,664)	(2,664)
Change in pension obligation					(43)	(43)
Exercise of stock options	$ 1	3,920				3,921
Exercise of stock options (in shares)	759
Issuance of shares under Employee Stock Purchase Plan		441				441
Issuance of shares under Employee Stock Purchase Plan (in shares)	47
Issuance of restricted common shares		(7)				(7)
Issuance of restricted common shares (in shares)	7
Stock-based compensation expense		5,582				5,582
Balance at Dec. 31, 2015	$ 29	529,089	(1,218)	(342,705)	(1,431)	183,764
Balance (in shares) at Dec. 31, 2015	29,026
Increase (Decrease) in Stockholders' Equity
Net income				11,001		11,001
Foreign currency translation adjustments					(847)	(847)
Change in pension obligation					(1)	(1)
Exercise of stock options	$ 1	2,237				2,238
Exercise of stock options (in shares)	392
Issuance of shares under Employee Stock Purchase Plan		325				325
Issuance of shares under Employee Stock Purchase Plan (in shares)	22
Issuance of restricted common shares		(11)				(11)
Issuance of restricted common shares (in shares)	108
Treasury shares returned to authorized, Value		(1,218)	$ 1,218
Treasury shares returned to authorized, Shares	(30)
Reverse stock split issuance costs		(145)				(145)
Stock-based compensation expense		5,131				5,131
Balance at Dec. 31, 2016	$ 30	535,408		(331,704)	(2,279)	201,455
Balance (in shares) at Dec. 31, 2016	29,518
Increase (Decrease) in Stockholders' Equity
Net income				126,959		126,959
Foreign currency translation adjustments					4,347	4,347
Change in pension obligation					108	108
Exercise of stock options	$ 2	15,512				15,514
Exercise of stock options (in shares)	2,358
Issuance of shares under Employee Stock Purchase Plan		845				845
Issuance of shares under Employee Stock Purchase Plan (in shares)	34
Issuance of restricted common shares		(1,164)				(1,164)
Issuance of restricted common shares (in shares)	138
Stock-based compensation expense		5,546				5,546
Balance at Dec. 31, 2017	$ 32	$ 556,147		$ (204,745)	$ 2,176	$ 353,610
Balance (in shares) at Dec. 31, 2017	32,048

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ 126,959	$ 11,001	$ 14,678
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	5,002	4,258	4,869
Gain on sale of equipment		(248)
Deferred taxes	(82,085)	519	779
Stock-based compensation expense	5,672	5,179	5,575
Provision for doubtful accounts		106
Provision for excess and obsolete inventory	(8,135)	1,051	1,721
Changes in operating assets & liabilities:
Accounts receivable	(23,573)	(14,135)	5,171
Inventories	5,703	(6,572)	(15,938)
Prepaid expenses and other current assets	(3,866)	(1,056)	640
Accounts payable and other current liabilities	25,000	810	6,005
Deferred revenue	7,079	2,467	1,360
Income taxes	14	102	(46)
Other assets and liabilities	(1,486)	(12,270)	(6,547)
Net cash provided by (used in) operating activities	56,284	(8,788)	18,267
Cash flows from investing activities
Proceeds from sale of equipment		270
Expenditures for property, plant and equipment and capitalized software	(7,285)	(2,506)	(1,830)
Net cash used in investing activities	(7,285)	(2,236)	(1,830)
Cash flows from financing activities
Net settlement on restricted stock grants	(1,184)	(11)	(8)
Financing fees and other expenses		(146)	(847)
Principal payments on term loan			(14,530)
Principal payments on sale leaseback obligation			(392)
Proceeds from financing obligations			48,940
Proceeds from Employee Stock Purchase Plan	739	277	441
Proceeds from exercise of stock options	15,515	2,227	3,921
Net cash provided by financing activities	15,070	2,347	37,525
Effect of exchange rate changes on cash and cash equivalents	(844)	507	285
Net increase (decrease) in cash, cash equivalents and restricted cash	63,225	(8,170)	54,247
Cash, cash equivalents and restricted cash at beginning of period	77,655	85,825	31,578
Cash, cash equivalents and restricted cash at end of period	140,880	77,655	85,825
Supplemental disclosure of cash flow information
Cash paid for Income taxes	583	525	669
Cash paid for Interest	$ 5,315	$ 4,815	$ 3,985

Nature of Business	12 Months Ended
Nature of Business	Dec. 31, 2017
Nature of Business
Nature of Business	Note 1. Nature of Business Axcelis Technologies, Inc. (“Axcelis” or the “Company”) was incorporated in Delaware in 1995, and is a worldwide producer of ion implantation and other processing equipment used in the fabrication of semiconductor chips in the United States, Europe and Asia. In addition, the Company provides extensive aftermarket service and support, including spare parts, equipment upgrades, used equipment and maintenance services to the semiconductor industry.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

Note 2. Summary of Significant Accounting Policies

The accompanying consolidated financial statements reflect the application of certain significant accounting policies as described in this note and elsewhere in the footnotes.

(a) Basis of Presentation

The accompanying consolidated financial statements include the consolidated accounts of the Company and its wholly‑owned, controlled subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Certain reclassifications have been made to prior years' financial statements to conform to the current year’s presentation.

Events occurring subsequent to December 31, 2017 have been evaluated for potential recognition or disclosure in the consolidated financial statements.

(b) Use of Estimates

The preparation of these consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the dates of the financial statements and the reported amounts of revenue and expenses during the reporting periods. On an ongoing basis, the Company evaluates its estimates and judgments, including those related to revenue recognition, the realizable value of inventories, valuing stock-based compensation instruments and reserves relating to tax assets and liabilities. Actual amounts could differ from these estimates. Changes in estimates are recorded in the period in which they become known.

The functional currency for substantially all operations outside the United States is the local currency. Financial statements for these operations are translated into United States dollars at year‑end rates as to assets and liabilities and average exchange rates during the year as to revenue and expenses. The resulting translation adjustments are recorded in stockholders’ equity as an element of accumulated other comprehensive income (loss). Foreign currency transaction gains and losses are included in other income (expense) in the Consolidated Statements of Operations.

For the year ended December 31, 2017 the Company had $1.1 million in foreign exchange gains. For the year ended December 31, 2016 the Company had $0.6 million in foreign exchange losses. For the year ended December 31, 2015 the Company did not have any material foreign exchange gains or losses.

(d) Cash and Cash Equivalents

Cash and cash equivalents consist of cash on hand and highly liquid investments with original maturities of ninety days or less. Cash equivalents consist primarily of money market funds, U.S Government and Agency Securities and deposit accounts. Cash equivalents are carried on the balance sheet at fair market value.

(e) Inventories

Inventories are carried at lower of cost or net realizable value, determined using the first‑in, first‑out (“FIFO”) method, or market. The Company periodically reviews its inventories and makes provisions as necessary for estimated obsolescence or damaged goods to ensure values approximate lower of cost or net realizable value. The amount of such markdowns is equal to the difference between cost of inventory and the estimated market value based upon assumptions about future demands, selling prices, and market conditions.

The Company records an allowance for estimated excess inventory. The allowance is determined using management’s assumptions of materials usage, based on estimates of demand and market conditions. If actual market conditions become less favorable than those projected by management, additional inventory write‑downs may be required.

(f) Property, Plant and Equipment

Property, plant and equipment are stated at cost, less accumulated depreciation and amortization.

Depreciation and amortization are recorded using the straight‑line method over the estimated useful lives of the related assets as follows:


Asset Classification	Estimated Useful Life
Land and buildings (under lease)		Lesser of the lease term or estimated useful life of the asset
Machinery and equipment		7 to 10 years

On January 30, 2015, the Company sold its corporate headquarters facility. As part of this sale, the Company also entered into a 22-year lease agreement. The Company accounted for the sale leaseback transaction as a financing arrangement for financial reporting purposes. The Company retained the historical costs of the property and the related accumulated depreciation on its financial books within property, plant and equipment and will continue to depreciate the property for financial reporting purposes over the lesser of its remaining useful life or its initial lease term of 22 years.

Repairs and maintenance costs are expensed as incurred. Expenditures for renewals and betterments are capitalized.

(g) Impairment of Long‑Lived Assets

The Company records impairment losses on long-lived assets when events and circumstances indicate that these assets might not be recoverable. Recoverability is measured by a comparison of the assets’ carrying amount to their expected future undiscounted net cash flows. If such assets are considered to be impaired, the impairment is measured based on the amount by which the carrying value exceeds its fair value.

The Company did not have any indicators of impairment during the period ending December 31, 2017. The Company did not record an impairment charge in the years ended December 31, 2017, 2016, or 2015.

Actual performance could be materially different from our current forecasts, which could impact estimates of undiscounted cash flows and may result in the impairment of the carrying amount of the long-lived assets in the future. This could be caused by strategic decisions made in response to economic and competitive conditions, the impact of the economic environment on our customer base, or a material adverse change in the Company’s relationships with significant customers.

(h) Concentration of Risk and Off‑Balance Sheet Risk

Financial instruments that potentially subject the Company to concentrations of credit risk are principally cash equivalents and accounts receivable. The Company’s cash equivalents are principally maintained in investment grade money‑market funds, U.S. Government and Agency Securities and deposit accounts.

The Company has no significant off‑balance‑sheet risk such as currency exchange contracts, option contracts or other hedging arrangements.

The Company’s exposure to market risk for changes in interest rates relates primarily to cash equivalents. The primary objective of the Company’s investment activities is to preserve principal without significantly increasing risk. This is accomplished by investing in marketable high investment grade securities. The Company does not use derivative financial instruments to manage its investment portfolio and does not expect operating results or cash flows to be affected to any significant degree by any change in market interest rates.

The Company performs ongoing credit evaluations of its customers’ financial condition and generally requires no collateral to secure accounts receivable. For selected overseas sales, the Company requires customers to obtain letters of credit before product is shipped. The Company maintains an allowance for doubtful accounts based on its assessment of the collectability of accounts receivable. The Company reviews the allowance for doubtful accounts quarterly. The Company does not have any off‑balance sheet credit exposure related to its customers.

The Company’s customers consist of semiconductor chip manufacturers located throughout the world and net sales to its ten largest customers accounted for 73.3%, 70.2% and 76.8% of revenue in 2017, 2016 and 2015, respectively.

For the year ended December 31, 2017 the Company had two customers representing 24.9% and 13.1% of total revenue, respectively. For the year ended December 31, 2016, the Company had one customer representing 17.0% of total revenue. For the year ended December 31, 2015, the Company had two customers representing 29.3% and 10.5% of total revenue, respectively.

As of December 31, 2017, the Company had three customers account for 19.8%, 11.8% and 10.6% of consolidated accounts receivable, respectively. As of December 31, 2016, the Company had four customers account for 22.0%, 12.3%, 12.0% and 10.6% of consolidated accounts receivable, respectively.

Some of the components and sub‑assemblies included in the Company’s products are obtained either from a sole source or a limited group of suppliers. Disruption to the Company’s supply source, resulting either from economic conditions or other factors, could affect its ability to deliver products to its customers.

(i) Revenue Recognition

The Company’s revenue recognition policy involves significant judgment by management. The Company considers a broad array of facts and circumstances in determining when to recognize revenue, including contractual obligations to the customer, the complexity of the customer’s post‑delivery acceptance provisions, payment history, customer creditworthiness and the installation process.

The Company’s system sales transactions are made up of multiple elements, including the system itself and elements that are not delivered simultaneously with the system. These undelivered elements might include a combination of installation services, extended warranty and support and spare parts, all of which are covered generally by a single sales price.

The Company’s system revenue arrangements with multiple elements are divided into separate units of accounting if specified criteria are met, including whether the delivered element has stand‑alone value to the customer. If the criteria are met, then the consideration received is allocated among the separate units based on their relative selling price, and the revenue is recognized separately for each of the separate units.

The Company determines selling price for each unit of accounting (element) using vendor specific objective evidence (VSOE) or third‑party evidence (TPE), if they exist, otherwise, the Company uses best estimated selling price (BESP). The Company generally expects that it will not be able to establish TPE due to the nature of its products, and, as such, the Company typically will determine selling price using VSOE or BESP.

Where required, the Company determines BESP for an individual element based on consideration of both market and Company‑specific factors, including the selling price and profit margin for similar products, the cost to produce the deliverable and the anticipated margin on that deliverable and the characteristics of the markets in which the deliverable is sold.

Systems are not sold separately and VSOE or TPE is not available for the systems element. Therefore the selling price associated with systems is based on BESP. The allocated value for installation in the arrangement includes either (i) the relative selling price of the installation or (ii) the portion of the sales price that will not be received until the installation is completed (the “retention”). The selling price of elements such as extended warranty for support, spare parts and support labor is also based on BESP. For the majority of regions, the selling price of installation is based upon the fair value of the service performed, including labor, which is based upon the estimated time to complete the installation at hourly rates, and material components, both of which are sold separately, or VSOE. In regions where VSOE does not exist the Company uses BESP.

Product revenue for products which have demonstrated market acceptance, is generally recognized upon shipment provided title and risk of loss has passed to the customer, evidence of an arrangement exists, prices are contractually fixed or determinable, collectability is reasonably assured through historical collection results and regular credit evaluations, and there are no uncertainties regarding customer acceptance. Revenue from installation services is recognized at the time acceptance has occurred, as defined in the sales documentation or, for certain customers, when both acceptance has occurred and retention payment has been received. Revenue for other elements is recognized at the time products are shipped or the related services are performed.

The Company generally recognizes revenue for systems which have demonstrated market acceptance at the time of shipment because the customer’s post‑delivery acceptance provisions and installation process have been established to be routine, commercially inconsequential and perfunctory. The Company believes the risk of failure to complete a system installation is remote.

For initial shipments of systems with new technologies or in the small number of instances where the Company is unsure of meeting the customer’s specifications or obtaining customer acceptance upon shipment of the system, it will defer the recognition of systems revenue and related costs until written customer acceptance of the system is obtained. This deferral period is generally within twelve months of shipment.

Revenue related to maintenance and service contracts is recognized ratably over the duration of the contracts, or based on parts usage, where appropriate. Revenue related to service hours is recognized when the services are performed.

Product revenue includes revenue from system sales, sales of spare parts, the spare parts component of maintenance and service contracts and product upgrades. Services revenue includes the labor component of maintenance and service contract amounts charged for on‑site service personnel.

Axcelis reports revenue net of any taxes collected from customers and remitted to governmental authorities, with the collected taxes recorded as current liabilities until remitted to the relevant government authority.

(j) Shipping and Handling Costs

Shipping and handling costs are included in cost of revenue.

(k) Stock‑Based Compensation

The Company generally recognizes compensation expense for all stock-based payments to employees and directors, including grants of stock options and restricted stock units, based on the grant‑date fair value of those stock‑based payments using the Black‑Scholes option pricing model, adjusted for expected forfeitures. Other valuation models may be utilized in the limited circumstances where awards with market-based vesting considerations, such as the price of the Company’s common stock, or performance based awards, are granted. Stock‑based compensation expense is recognized ratably over the requisite service period. For each stock option or restricted stock unit grant with vesting based on a combination of time, market or performance conditions, where vesting will occur if either condition is met, the related compensation costs are recognized over the shorter of the explicit service period or the derived service period.

See Note 11 for additional information relating to stock‑based compensation.

(l) Income Taxes

The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax basis, and operating loss and tax credit carryforwards.

The Company’s consolidated financial statements contain certain deferred tax assets which have arisen primarily as a result of operating losses, as well as other temporary differences between financial and tax accounting. The Company establishes a valuation allowance if the likelihood of realization of the deferred tax assets is reduced based on an evaluation of objective verifiable evidence. Significant management judgment is required in determining the Company’s provision for income taxes, the Company’s deferred tax assets and liabilities and any valuation allowance recorded against those net deferred tax assets. The Company evaluates the weight of all available evidence to determine whether it is more likely than not that some portion or all of the net deferred income tax assets will not be realized.

Income taxes include the largest amount of tax benefit for an uncertain tax position that is more likely than not to be sustained upon audit based on the technical merits of the tax position. Settlements with tax authorities, the expiration of statutes of limitations for particular tax positions, or obtaining new information on particular tax positions may cause a change to the effective tax rate. The Company recognizes accrued interest related to unrecognized tax benefits as interest expense and penalties as operating expense in the consolidated statements of operations.

(m) Computation of Net Income per Share

Basic earnings per share is computed by dividing income available to common stockholders (the numerator) by the weighted‑average number of common shares outstanding (the denominator) for the period. The computation of diluted earnings per share is similar to basic earnings per share, except that the denominator is increased to include the number of additional common shares that would have been outstanding if the potentially dilutive common shares had been issued, calculated using the treasury stock method.

The components of net income per share are as follows:


	Year ended December 31,
	2017		2016		2015
	(in thousands, except per share data)
Net income available to common stockholders	$	126,959	$	11,001	$	14,678
Weighted average common shares outstanding used in computing basic income per share		30,866		29,195		28,595
Incremental options and RSUs		2,570		1,752		1,634
Weighted average common shares used in computing diluted net income per share		33,436		30,947		30,229
Net income per share
Basic	$	4.11	$	0.38	$	0.51
Diluted	$	3.80	$	0.36	$	0.49

Diluted weighted average common shares outstanding does not include options and restricted stock units

outstanding to purchase 0.9 million and 0.9 million common equivalent shares for the periods ended December 31, 2016 and 2015, respectively, as their effect would have been anti-dilutive.

(n) Accumulated Other Comprehensive Income

The following table presents the changes in accumulated other comprehensive income, net of tax, by component for the year ended December 31, 2017:


	Foreign		Defined benefit
	currency		pension plan		Total
	(in thousands)
Balance at December 31, 2016	$	(1,591)	$	(688)	$	(2,279)
Other comprehensive income and pension reclassification		4,347		108		4,455
Balance at December 31, 2017	$	2,756	$	(580)	$	2,176

(o) Recent Accounting Guidance

Accounting Standards or Updates Recently Adopted

In July 2015, the FASB issued Accounting Standards Update (ASU) No. 2015-11, “Simplifying the Measurement of Inventory,” which changes the inventory measurement principles for entities using the first-in, first-out (FIFO) or average cost methods. For entities utilizing one of these methods, the inventory measurement principle changes from lower of cost or market to the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less the reasonably predictable costs of completion, disposal and transportation. The Company adopted this ASU prospectively in the first quarter of 2017, which did not have a material impact on our financial statements and disclosures.

In March 2016, the FASB issued ASU No. 2016-09 “Compensation — Stock Compensation,” which changes the accounting for stock-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The amended guidance eliminates the requirement to record excess tax benefits as a reduction in current taxes payable and an increase to additional paid-in capital. The Company adopted this ASU in the first quarter of 2017, in part prospectively and in part retrospectively, as permitted by the ASU.

The Company prospectively adopted the provisions of ASU No. 2016-09 relating to the accounting for excess tax benefits. Axcelis had tax deductions in excess of recognized compensation cost of $29.5 million for the year ended December 31, 2017 which resulted in a tax benefit of $10.3 million.

The Company retrospectively adopted the provisions of ASU 2016-09 related to the presentation of employee taxes. These provide that when an employer withholds shares for taxes on vesting of equity compensation, the value withheld is presented as a financing activity on the statement of cash flows. This resulted in a $1.2 million, eleven thousand and an eight thousand dollar reduction in net cash provided by financing activities for the years ended December 31, 2017, 2016 and 2015, respectively. Prior to adoption, these amounts were reflected within cash flows from operating activities.

The Company has also elected to continue to estimate a forfeiture rate associated with our stock-based awards and related expense.

In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 203): Restricted Cash (a consensus of the FASB Emerging Issues Task Force).” This ASU requires the statement of cash flows to explain the change during the period in the total cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents are to be included with cash and cash equivalents when reconciling the beginning of period and end of period amounts shown on the statement of cash flows. On January 1, 2017, the Company early adopted this ASU retrospectively, resulting in $6.9 million of restricted cash being included in the beginning balances of cash, cash equivalents and restricted cash balances on the statement of cash flows for the periods presented. Please see Note 3 for additional information.

Accounting Standards or Updates Not Yet Effective

In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers,” which provides guidance for revenue recognition. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In April 2016, the FASB issued ASU 2016-10, “Revenue from Contracts with Customers” (Topic 606): Identifying Performance Obligations and Licensing, which further clarifies performance obligations in a contract with a customer. In May 2016, the FASB issued ASU 2016-12, “Revenue from Contracts with Customers” (Topic 606): Narrow-Scope Improvements and Practical Expedients, which provides a more narrow interpretation of ASU No. 2014-09. In July, 2017, the FASB issued ASU 2017-13, “Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842), which clarifies the transition periods related to public and private business entities. These ASUs (collectively referred to as “Topic 606”) are effective for annual reporting periods beginning after December 15, 2017 and interim periods within those annual periods.

The Company has substantially completed the implementation of Topic 606 and has identified the necessary changes to its policies, processes, systems, and controls.

The Company will adopt Topic 606, effective January 1, 2018, using the modified retrospective approach. The cumulative effect of adopting Topic 606 will be a $1.6 million increase to retained earnings on January 1, 2018. We have completed our assessment of the effect of adoption. Based on our assessment, under ASC 606 we will no longer value any installation performance obligation as the greater of the standalone selling price or retention, but rather only value installation at the standalone selling price.

In February 2016, the FASB issued ASU No. 2016-02 “Leases.” In July, 2017, the FASB issued ASU 2017-13, “Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842), which clarifies the transition periods related to public and private business entities. The ASU requires lessees to recognize the rights and obligations created by most leases as assets and liabilities on their balance sheet and continue to recognize expenses on their income statement over the lease term. It will also require disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. The guidance is effective for annual reporting periods beginning after December 15, 2018, and interim periods within those years. Early adoption is permitted for all entities. We are currently evaluating the impact of ASU 2016-02 on the consolidated financial statements and disclosures.

In August 2016, the FASB issued ASU No. 2016-15 “Classification of Certain Cash Receipts and Cash Payments.” The ASU is intended to add or clarify guidance on the classification of certain receipts and payments in the statement of cash flows and to eliminate the diversity in practice related to such classifications. The guidance in ASU 2016-15 is required for annual reporting periods beginning after December 15, 2017, with early adoption permitted. We are currently evaluating the impact of ASU 2016-15 on the consolidated financial statements and disclosures.

In March 2017, the FASB issued ASU No. 2017-07 “Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” The ASU is intended to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. The amendment applies to all entities offering a defined benefit pension plan, other postretirement benefit plans, or other types of benefits accounted for under Topic 715. The amendments in the ASU require an employer to report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. The amendments in this ASU are effective for public business entities for annual periods beginning after December 15, 2017, including interim periods within the annual period. The amendments in this ASU should be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively, on and after the effective date, for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. We are currently evaluating the impact of ASU 2017-07 on the consolidated financial statements and disclosures.

Cash, cash equivalents and restricted cash

12 Months Ended

Dec. 31, 2017

Cash, cash equivalents and restricted cash

Cash, cash equivalents and restricted cash

Note 3. Cash, cash equivalents and restricted cash


	December 31,
	2017			2016
	(dollars in thousands)
Cash and cash equivalents	$	133,407	$	70,791
Short-term and long-term restricted cash		7,473		6,864
Total cash, cash equivalents and restricted cash	$	140,880	$	77,655

As of December 31, 2017, the Company had $7.5 million in restricted cash which relates to a $5.9 million letter of credit associated with the security deposit for the sale leaseback transaction, a $0.8 million letter of credit relating to workers’ compensation insurance, a $0.7 million letter of credit associated with a bank guarantee and a $0.1 million deposit relating to customs activity.

Accounts Receivable, net

12 Months Ended

Dec. 31, 2017

Accounts Receivable, net

Accounts Receivable, net

Note 4. Accounts Receivable, net

The components of accounts receivable are as follows:


	December 31,
	2017		2016
	(in thousands)
Trade receivables	$	75,302	$	50,650
Allowance for doubtful accounts		—		(77)
Trade receivables, net	$	75,302	$	50,573

We record an allowance for doubtful accounts for estimated losses resulting from the inability of our customers to make required payments. Our allowance for doubtful accounts is established based on a specific assessment of collectability of our customer accounts. If the financial condition of our customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be necessary.

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventories, net

12 Months Ended

Dec. 31, 2017

Inventories, net

Inventories, net

Note 5. Inventories, net

The components of inventories are as follows:


	December 31,
	2017		2016
	(in thousands)
Raw materials	$	82,313	$	80,503
Work in process		31,651		14,117
Finished goods (completed systems)		6,580		19,233
Inventories, net	$	120,544	$	113,853

When recorded, inventory reserves are intended to reduce the carrying value of inventories to their net realizable value. The Company establishes inventory reserves when conditions exist that indicate inventory may be in excess of anticipated demand or is obsolete based upon assumptions about future demand for the Company’s products or market conditions. The Company regularly evaluates the ability to realize the value of inventories based on a combination of factors including the following: forecasted sales or usage, estimated product end of life dates, estimated current and future market value and new product introductions. Purchasing and usage alternatives are also explored to mitigate inventory exposure. In 2017, the Company recorded a net increase of $5.3 million in inventory reserves, which includes $6.2 million of write-down of excess inventory related to Legacy products. As of December 31, 2017 and 2016, inventories are stated net of inventory reserves of $14.2 million and $8.8 million respectively.

During each of the years ended 2017, 2016 and 2015, the Company recorded charges to cost of sales of $8.1 million, $0.8 million and $0.5 million to reflect the lower of cost or net realizable value.

The Company has inventory on consignment at customer locations as of December 31, 2017 and 2016, of $3.6 million and $3.4 million, respectively.

Property, Plant and Equipment, net

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment, net.

Property, Plant and Equipment, net

Note 6. Property, Plant and Equipment, net

The components of property, plant and equipment are as follows:


	December 31,
	2017		2016
	(in thousands)
Land and buildings	$	76,260	$	75,792
Machinery and equipment		11,477		9,472
Construction in process		6,982		1,704
Total cost		94,719		86,968
Accumulated depreciation		(58,551)		(56,128)
Property, plant and equipment, net	$	36,168	$	30,840

Depreciation expense was $2.2 million, $1.8 million and $2.4 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Assets Manufactured for Internal Use, net

12 Months Ended

Dec. 31, 2017

Assets Manufactured for Internal Use, net

Assets Manufactured for Internal Use, net

Note 7. Assets Manufactured for Internal Use, net

The components of assets manufactured for internal use, included in amounts reported as other assets, are as follows:


	December 31,
	2017		2016
	(in thousands)
Internal use assets	$	40,366	$	42,776
Construction in process		301		1,745
Total cost		40,667		44,521
Accumulated depreciation		(20,035)		(22,838)
Assets manufactured for internal use, net	$	20,632	$	21,683

These products are used for research and development, training, and customer demonstration purposes.

Depreciation expense was $2.8 million, $2.4 million and $2.5 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Product Warranty

12 Months Ended

Dec. 31, 2017

Product Warranty

Product Warranty

Note 8. Product Warranty

The Company generally offers a one year warranty for all of its systems, the terms and conditions of which vary depending upon the product sold. For all systems sold, the Company accrues a liability for the estimated cost of standard warranty at the time of system shipment and defers the portion of systems revenue attributable to the fair value of non‑standard warranty. Costs for non‑standard warranty are expensed as incurred. Factors that affect the Company’s warranty liability include the number of installed units, historical and anticipated product failure rates, material usage and service labor costs. The Company periodically assesses the adequacy of its recorded liability and adjusts the amount as necessary.

The changes in the Company’s product warranty liability are as follows:



	Year ended December 31,
	2017		2016		2015
	(in thousands)
Balance at January 1 (beginning of year)	$	2,666	$	3,555	$	1,526
Warranties issued during the period		5,671		3,125		4,305
Settlements made during the period		(2,603)		(4,249)		(2,672)
Changes in estimate of liability for pre-existing warranties during the period		(1,232)		235		396
Balance at December 31 (end of period)	$	4,502	$	2,666	$	3,555

Amount classified as current	$	4,112	$	2,426	$	3,363
Amount classified as long-term		390		240		192
Total warranty liability	$	4,502	$	2,666	$	3,555

Financing Arrangements	12 Months Ended
Financing Arrangements	Dec. 31, 2017
Financing Arrangements
Financing Arrangements	Note 9. Financing Arrangements Sale Leaseback Obligation On January 30, 2015, the Company sold its corporate headquarters facility for the purchase price of $48.9 million. As part of the sale, the Company also entered into a 22-year lease agreement with the buyer. The sale leaseback is accounted for as a financing arrangement for financial reporting and, as such, the Company recorded a financing obligation of $47.7 million as of December 31, 2017. The associated lease payments include both an interest component and payment of principal, with the underlying liability being extinguished at the end of the original lease term. The Company posted a collateralized security deposit of $5.9 million in the form of an irrevocable letter of credit at the time of the closing. In October 2015, this letter of credit was cash collateralized.

Employee Benefit Plans

12 Months Ended

Dec. 31, 2017

Employee Benefit Plans

Employee Benefit Plans

Note 10. Employee Benefit Plans

(a) Defined Contribution Plan

The Company maintains the Axcelis Long-Term Investment Plan, a defined contribution plan. All regular employees are eligible to participate and may contribute up to 35% of their compensation on a before-tax basis subject to Internal Revenue Service (“IRS”) limitations. Highly compensated employees may contribute up to 16% of their compensation on a before-tax basis subject to IRS limitations. In 2015, the Company implemented a matching contribution of up to one thousand U.S. dollars on a dollar-for-dollar basis on contributions by eligible participants. In 2016, the Company increased the matching contribution to a maximum of $1,200, on the basis of one dollar matched for each two dollars contributed by eligible participants. In 2017, the Company increased the matching contribution to 50% of employees’ pre-tax contributions on the first 6% of eligible compensation contributed to the plan. Total related expense was $0.5 million, $0.4 million and $0.4 million, for 2017, 2016 and 2015, respectively.

(b) Other Compensation Plans

The Company operates in foreign jurisdictions that require lump sum benefits, payable based on statutory regulations, for voluntary or involuntary termination. Where required, an annual actuarial valuation of the benefit plans is obtained.

The Company has recorded an unfunded liability of $4.6 million and $4.0 million at December 31, 2017 and 2016, respectively, for costs associated with these compensation plans in foreign jurisdictions. The following table presents the classification of these liabilities in the Consolidated Balance Sheets:


	Year ended
	December 31,
	2017		2016
	(in thousands)
Current:
Accrued compensation	$	967	$	902
Total current liabilities	$	967	$	902
Long-term:
Other long-term liabilities		3,583		3,057
Total liabilities	$	4,550	$	3,959

The expense recorded in connection with these plans was $1.0 million, $0.8 million and $0.7 million during the years ended December 31, 2017, 2016 and 2015, respectively.

Stock Award Plans and Stock Based Compensation

12 Months Ended

Dec. 31, 2017

Stock Award Plans and Stock Based Compensation

Stock Award Plans and Stock Based Compensation

Note 11. Stock Award Plans and Stock Based Compensation

(a) Equity Incentive Plans

The Company maintains the Axcelis Technologies, Inc. 2012 Equity Incentive Plan (the “2012 Equity Plan”), which became effective on May 2, 2012. Our 2000 Stock Plan (the “2000 Stock Plan”) expired on May 1, 2012 and no new grants may be made under that plan after that date. However, awards granted under the 2000 Stock Plan prior to the expiration remain outstanding and subject to the terms of the 2000 Stock Plan.

The 2012 Equity Plan, as amended, reserves 6.5 million shares of common stock, $0.001 par value, for grant and permits the issuance of options, stock appreciation rights, restricted stock, restricted stock units, stock equivalents and awards of shares of common stock that are not subject to restrictions or forfeiture to selected employees, directors and consultants of the Company. In accordance with the terms of the 2012 Equity Plan, this reserves shares that were not issued under an award (because such award expires, is terminated unexercised or is forfeited) that was outstanding under the 2000 Stock Plan as of the May 2, 2012.

The term of stock options granted under these plans is specified in the award agreements. Unless a lesser term is otherwise specified by the Compensation Committee of the Company’s Board of Directors, awards under the 2012 Equity Plan will expire seven years from the date of grant. In general, all awards issued under the 2000 Stock Plan expire ten years from the date of grant. Under the terms of these stock plans, the exercise price of a stock option may not be less than the fair market value of a share of the Company’s common stock on the date of grant. Under the 2012 Equity Plan, fair market value is defined as the last reported sale price of a share of the common stock on a national securities exchange as of any applicable date, as long as the Company’s shares are traded on such exchange.

Stock options granted to employees generally vest over a period of four years, while stock options granted to non‑employee members of the Company’s Board of Directors generally vest over a period of six months and, once vested, are not affected by the director’s termination of service to the Company. In limited circumstances, the Company may grant stock option awards with market-based vesting conditions, such as the Company’s common stock price, or other performance conditions. Termination of service by an employee will cause options to cease vesting as of the date of termination, and in most cases, employees will have 90 days after termination to exercise options that were vested as of the termination of employment. In general, retiring employees will have one year after termination of employment to exercise vested options. The Company settles stock option exercises with newly issued common shares.

Restricted stock units granted to employees during 2017 had both time-based vesting provisions and performance-based vesting provisions. Generally, unvested restricted stock unit awards expire upon termination of service to the Company. The Company settles restricted stock units upon vesting with newly issued common shares. No restricted stock was granted under either stock plan during the three year period ended December 31, 2017.

As of December 31, 2017, there were 1.3 million shares available for grant under the 2012 Equity Plan. No shares are available for grant under the 2000 Stock Plan.

As of December 31, 2017, there were 2.6 million options outstanding under the 2012 Equity Plan and the 2000 Stock Plan, collectively, and 0.6 million unvested restricted stock units outstanding under the 2012 Stock Plan.

(b) Employee Stock Purchase Plan

The Employee Stock Purchase Plan (the “Purchase Plan”) provides effectively all of the Company’s employees the opportunity to purchase common stock of the Company at less than market prices. Purchases are made through payroll deductions of up to 10% of the employee’s salary as elected by the participant, subject to certain caps set forth in the Purchase Plan. Employees may purchase the Company’s common stock at 85% of its market on the day the stock is purchased.

The Purchase Plan is considered compensatory and as such, compensation expense has been recognized based on the benefit of the discounted stock price, amortized to compensation expense over each offering period of six months. Compensation expense relating to the Purchase Plan was approximately $0.1 million for each of the years ended December 31, 2017, 2016 and 2015.

As of December 31, 2017, there were a total of 0.3 million shares reserved for issuance and available for purchase under the Purchase Plan. Less than 0.1 million shares were purchased under the Purchase Plan in each of the years ended December 31, 2017, 2016 and 2015. The Purchase Plan will expire in June 2020, unless re-approved by the stockholders.

For the purpose of valuing stock options with service conditions, the Company uses the Black‑Scholes option pricing model to calculate the grant‑date fair value of an award. The fair values of options granted were calculated using the following estimated weighted‑average assumptions:


	Year ended December 31,
	2017	2016	2015
Weighted-average expected volatility	N/A	49.3% — 56.7%	56.2% — 64.7%
Weighted-average expected term	N/A	4.7 years	4.6 — 4.7 years
Risk-free interest rate	N/A	1.1% — 2.0%	1.3% — 1.6%
Expected dividend yield	N/A	0%	0%

Expected volatility—The Company considers a number of factors when estimating volatility for stock options granted. The Company’s method of estimating expected volatility relies on a combination of historical and implied volatility. The Company believes that this blended volatility results in an accurate estimate of the grant‑date fair value of employee stock options because it appropriately reflects the market’s current expectations of future volatility.

Expected term—The Company calculated the weighted average expected term for stock options granted prior to July 1, 2012, using a forward looking lattice model of the Company’s stock price incorporating a suboptimal exercise factor and a projected post‑vest forfeiture rate. For stock options granted after July 1, 2012 to employees and to non‑employee members of the Company’s Board of Directors, the Company used the simplified method for estimating the expected life of “plain vanilla” options because it did not have sufficient exercise history to use a lattice model. The Company expects that it will use a lattice model once sufficient exercise history has been established. A change in the contractual life from 10 years to 7 years was made to reflect the fact that options granted after May 1, 2012 were granted under the 2012 Equity Incentive Plan, which limits option terms to seven years.

Risk‑free interest rate - The yield on zero‑coupon U.S. Treasury securities for a period that is commensurate with the expected term assumption is used as the risk‑free interest rate.

Expected dividend yield—Expected dividend yield was not considered in the option pricing formula since the Company does not pay dividends and has no current plans to do so in the future.

In limited circumstances, the Company also issues stock option grants with vesting based on market conditions, such as the Company’s common stock price, or a combination of time or market or performance conditions. The fair values and derived service periods for all grants that have vesting based on market or performance conditions are estimated using the Monte Carlo valuation method. For each stock option grant with vesting based on a combination of time and performance or market conditions, where vesting will occur if either condition is met, the related compensation costs are recognized over the shorter of the explicit service period or the derived service period.

The fair value of the Company’s restricted stock units is calculated based upon the fair market value of the Company’s stock at the date of grant.

(d) Summary of Stock-based Compensation Expense

The Company uses the straight‑line attribution method to recognize expense for stock‑based awards such that the expense associated with awards is evenly recognized throughout the period.

The amount of stock‑based compensation recognized is based on the value of the portion of the awards that are ultimately expected to vest. The Company estimates forfeitures at the time of grant and revises them, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The term “forfeitures” is distinct from “cancellations” or “expirations” and represents only the unvested portion of the surrendered stock‑based award. Based on a historical analysis, a forfeiture rate of 5% per year was applied to stock‑based awards, including executive officer awards, for the years ended December 31, 2017, 2016 and 2015.

For the year ended December 31, 2017, the Company recognized stock-based compensation expense of $5.7 million. Stock-based compensation expense was $5.2 million and $5.6 million for the years ended December 31, 2016 and 2015, respectively. The Company presents the expenses related to stock-based compensation in the same expense line items as cash compensation paid to its employees. For the year ended December 31, 2017, the Company used restricted stock units in its annual equity compensation program. For the year ended December 31, 2016, the Company primarily used restricted stock units in its annual equity compensation program. For the year ended December 31, 2015, the Company primarily used stock options in its annual equity compensation program.

The benefit of tax deductions in excess of recognized compensation cost is reported as a financing cash flow, rather than as an operating cash flow. Axcelis had tax deductions in excess of recognized compensation cost of $29.5 million for the year ended December 31, 2017 which resulted in a tax benefit of $10.3 million. Because the Company did not recognize the benefit of tax deductions in excess of recognized compensation cost due to its cumulative net operating loss position, this had no impact on the Company’s consolidated statement of cash flows as of and for the years ended December 31, 2017, 2016 and 2015.

(e) Stock Option Awards

The following table summarizes the stock option activity for the year ended December 31, 2017:


				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
		Exercise		Contractual	Intrinsic
	Options	Price		Term	Value
	(in thousands)			(years)	(in thousands)
Outstanding at December 31, 2016	4,951	$	7.29
Granted	—		—
Exercised	(2,358)		6.58
Canceled	(15)		10.24
Expired	(2)		21.32
Outstanding at December 31, 2017	2,576	$	7.91	3.21	$	53,571
Exercisable at December 31, 2017	2,008	$	7.16	2.92	$	43,236
Options Vested or Expected to Vest at December 31, 2017(1)	2,555	$	7.88	3.25	$	53,189

(1) In addition to the vested options, the Company expects a portion of the unvested options to vest at some point in the future. Options expected to vest is calculated by applying an estimated forfeiture rate to the unvested options.

The total intrinsic value, which is defined as the difference between the market price at exercise and the price paid by the employee to exercise the options, for options exercised during the years ended December 31, 2017, 2016 and 2015 was $39.7 million, $2.5 million and $5.3 million, respectively.

The total fair value of stock options vested during the years ended December 31, 2017, 2016 and 2015 was $3.1 million, $3.9 million and $5.4 million respectively. The weighted average grant-date fair value of options granted for the years ended December 31, 2016 and 2015 was $5.75 and $5.05, respectively. As of December 31, 2017, there was $2.3 million of total forfeiture‑adjusted unrecognized compensation cost related to non‑vested stock options granted under the 2012 Equity Incentive Plan and the 2000 Stock Plan. That cost is expected to be recognized over a weighted‑average period of 1.4 years.

(f) Restricted Stock and Restricted Stock Units

Restricted stock units (“RSUs”) represent the Company’s unfunded and unsecured promise to issue shares of the common stock at a future date, subject to the terms of the RSU Award Agreement in either the 2012 Equity Incentive Plan. The purpose of these awards is to assist in attracting and retaining highly competent employees and directors and to act as an incentive in motivating selected employees and directors to achieve long-term corporate objectives. RSU awards granted in 2017 included time vested share awards and awards with performance vesting conditions. No restricted stock awards were granted, or vested, during the years ended December 31, 2017, 2016 and 2015. The fair value of a restricted stock unit and restricted stock award is charged to expense ratably over the applicable service period.

Changes in the Company’s non‑vested restricted stock units for the year ended December 31, 2017 is as follows:


		Weighted-Average
		Grant Date Fair
	Shares/units	Value per Share
	(in thousands)
Outstanding at December 31, 2016	548	$	9.85
Granted	320		20.72
Vested	(196)		11.32
Forfeited	(55)		10.36
Outstanding at December 31, 2017	617	$	14.93

The weighted average grant-date fair value of restricted stock units granted for the years ended December 31, 2017, 2016 and 2015 was $20.72, $9.73 and $12.12, respectively. Some restricted stock units provide for net share settlement to offset the personal income tax obligations of the employee’s restricted stock unit vesting. Vesting activity above reflects shares vested before net share settlement.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2017
Stockholders' Equity
Stockholders' Equity	Note 12. Stockholders’ Equity The Company may issue up to 75 million shares of common stock without additional shareholder approval. As of December 31, 2017 and 2016, there were 32.0 million and 29.5 million outstanding shares of common stock.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Measurements

Fair Value Measurements

Note 13. Fair Value Measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.

(a) Fair Value Hierarchy

The accounting guidance for fair value measurement requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard establishes a fair value hierarchy based on the level of independent, objective evidence surrounding the inputs used to measure fair value. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The fair value hierarchy is as follows:

Level 1—applies to assets or liabilities for which there are quoted prices in active markets for identical assets or liabilities.

Level 2—applies to assets or liabilities for which there are inputs other than quoted prices that are observable for the asset or liability, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical assets or liabilities in markets with insufficient volume or infrequent transactions (less active markets); or model‑derived valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data.

Level 3—applies to assets or liabilities for which there are unobservable inputs to the valuation methodology that are significant to the measurement of the fair value of the assets or liabilities.

(b) Assets and Liabilities Measured at Fair Value

The Company’s money market funds and short-term investments are included in cash and cash equivalents in the consolidated balance sheets, and are considered a level 1 investment as they are valued at quoted market prices in active markets.

The following table sets forth Company’s assets and liabilities which are measured at fair value by level within the fair value hierarchy.


	December 31, 2017
	Fair Value Measurements
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash equivalents:
Money market funds, U.S. Government Securities and Agency Investments	$	116,433	$	—	$	—	$	116,433


	December 31, 2016
	Fair Value Measurements
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash equivalents:
Money market funds	$	54,170	$	—	$	—	$	54,170

The carrying amounts reflected in the consolidated balance sheets for accounts receivable, prepaid expenses and other current and non‑current assets, restricted cash, accounts payable and accrued expenses approximate fair value due to their short‑term maturities.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies

Commitments and Contingencies

Note 14. Commitments and Contingencies

(a) Lease Commitments

The Company leases manufacturing and office facilities and certain equipment under operating leases that expire through 2037. Rental expense was $3.9 million, $3.8 million and $3.8 million under operating leases for the years ended December 31, 2017, 2016 and 2015, respectively. Future minimum lease commitments on non‑cancelable operating leases for the year ended December 31, 2017 are as follows:


	Operating
	Leases
	(in thousands)
2018	$	2,915
2019		1,836
2020		894
2021		420
2022		202
Thereafter		39
	$	6,306

(b) Sale Leaseback Financing Obligation

In addition to the lease commitments as described above, the Company entered into a 22-year lease agreement relating to our corporate headquarters in Beverly, Massachusetts. The following table relates to the cash payment schedule associated with this lease obligation as of December 31, 2017:


	Lease
	Obligation
	(in thousands)
2018	$	5,471
2019		5,594
2020		5,719
2021		5,848
2022		5,980
Thereafter		92,020
Total lease payments	$	120,632
Less interest portion		(72,918)
Sale leaseback obligation	$	47,714

The Company has non‑cancelable contracts and purchase orders for inventory of $83.5 million at December 31, 2017.

(d) Litigation

The Company is not presently a party to any litigation that it believes might have a material adverse effect on its business operations. The Company is, from time to time, a party to litigation that arises in the normal course of its business operations.

(e) Indemnifications

The Company’s system sales agreements typically include provisions under which the Company agrees to take certain actions, provide certain remedies and defend its customers against third‑party claims of intellectual property infringement under specified conditions and to indemnify customers against any damage and costs awarded in connection with such claims. The Company has not incurred any material costs as a result of such indemnifications and has not accrued any liabilities related to such obligations in the accompanying consolidated financial statements.

Business Segment and Geographic Region Information

12 Months Ended

Dec. 31, 2017

Business Segment and Geographic Region Information

Business Segment and Geographic Region Information

Note 15. Business Segment and Geographic Region Information

The Company operates in one business segment, which is the manufacture of capital equipment for the semiconductor chip manufacturing industry. The principal market for semiconductor capital equipment is semiconductor chip manufacturers. Substantially all sales are made directly by the Company to its customers located in the United States, Europe and Asia Pacific.

The Company’s ion implantation systems product line includes high current, medium current and high energy implanters. Other products include legacy dry strip equipment, curing systems, and thermal processing systems. In addition to new equipment, the Company provides post‑sales equipment service and support, including spare parts, equipment upgrades, used equipment, maintenance services and customer training.

Revenue by product lines is as follows:


	Year ended December 31,
	2017		2016		2015
	(in thousands)
Ion implantation systems and services	$	391,051	$	248,885	$	282,624
Other systems and services		19,510		18,095		18,871
Total revenue	$	410,561	$	266,980	$	301,495

Revenue and long‑lived assets by geographic region, based on the physical location of the operation recording the sale or the asset, are as follows:


			Long-Lived
	Revenue		Assets
	(in thousands)
2017
United States	$	313,916	$	56,089
Europe		26,936		—
Asia Pacific		69,709		707
	$	410,561	$	56,796
2016
United States	$	191,261	$	52,006
Europe		25,436		—
Asia Pacific		50,283		517
	$	266,980	$	52,523
2015
United States	$	226,890	$	41,729
Europe		24,209		—
Asia Pacific		50,396		334
	$	301,495	$	42,063

Long‑lived assets consist of property, plant and equipment, net, and assets manufactured for internal use. Operations in Europe and Asia Pacific consist of sales and service organizations.

International revenue, which includes export sales from U.S. manufacturing facilities to foreign customers and sales by foreign subsidiaries and branches, was $348.5 million (84.9% of total revenue), $213.8 million (80.0% of total revenue) and $256.5 million (85.1% of total revenue) in 2017, 2016 and 2015, respectively.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
-Paragraph 41
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Taxes

Income Taxes

Note 16. Income Taxes

Income before income taxes is as follows:


	Year ended December 31,
	2017		2016		2015
	(in thousands)
United States	$	40,752	$	8,880	$	12,708
Foreign		3,079		2,144		2,497
Income before income taxes	$	43,831	$	11,024	$	15,205

Provision for income taxes is as follows:


	Year ended December 31,
	2017		2016		2015
	(in thousands)
Current:
United States
Federal	$	430	$	—	$	—
State		32		49		(33)
Foreign		230		(217)		374
Total current		692		(168)		341
Deferred:
Federal		(82,048)		—		—
State		(1,698)		—		—
Foreign		(74)		191		186
Total deferred		(83,820)		191		186
Income tax provision	$	(83,128)	$	23	$	527

Reconciliations of income taxes at the United States Federal statutory rate to the effective income tax rate are as follows:


	Year ended December 31,
	2017		2016		2015
	(in thousands)
Income tax benefit at the United States statutory rate	$	15,341	$	3,859	$	5,322
State income taxes		203		32		(22)
Unrecognized tax benefits		(285)		(615)		(174)
Effect of change in valuation allowance		(115,831)		(7,765)		(5,676)
Foreign income tax rate differentials		(312)		233		600
Unremitted earnings of foreign subsidiaries		(8,933)		305		(102)
Stock options		(10,342)		264		379
Credit expirations		—		3,565		—
Repatriation of foreign earnings		4,556		—		—
Recognition of equity NOL's		(1,165)		—		—
Rate change		42,531		—		—
Credit generation		(8,778)		—		—
Discrete items, net		31		—		(540)
Other, net		(144)		145		740
Income tax provision	$	(83,128)	$	23	$	527

Significant components of long‑term deferred income taxes are as follows:


	Year ended December 31,
	2017		2016


Federal net operating loss carryforwards	$	56,646	$	98,007
State net operating loss carryforwards		1,586		1,546
Foreign net operating loss carryforwards		758		673
Federal tax credit carryforwards		14,312		12,778
State tax credit carryforwards		6,908		2,566
Unremitted earnings of foreign subsidiaries		(21)		(8,913)
Intangible assets		116		229
Property, plant and equipment		5,838		9,774
Accrued compensation		45		97
Inventories		3,798		5,230
Stock compensation		2,351		6,687
Warranty		980		930
Deferred revenue		187		—
Other		(3,220)		(5,578)
Deferred taxes, gross		90,284		124,026
Valuation allowance		(7,136)		(122,966)
Deferred taxes, net	$	83,148	$	1,060

Changes in tax rates and tax laws are accounted for in the period of enactment. Our deferred tax assets and liabilities are measured at the enacted tax rate expected to apply when these temporary differences are expected to be realized or settled. On December 22, 2017, the Tax Cuts and Jobs Act (“2017 Tax Act”) was signed into law and has resulted in significant changes to the U.S. corporate income tax system. The 2017 Tax Act eliminates the deferral of U.S. income tax on the historical un-repatriated earnings by imposing the Transition Toll Tax, which is a one-time mandatory deemed repatriation tax on undistributed foreign earnings. The Transition Toll Tax is assessed on the U.S. shareholder's share of the foreign corporation's accumulated foreign earnings that have not previously been taxed. Earnings in the form of cash and cash equivalents will be taxed at a rate of 15.5% and all other earnings will be taxed at a rate of 8.0%. As of December 31, 2017, we have accrued income tax liabilities of $0.4 million under the Transition Toll Tax after utilization of foreign tax credits and research and development credits. The Transition Toll Tax will be paid over an eight-year period, starting in 2018, and will not accrue interest.

Our preliminary estimate of the Transition Toll Tax and the remeasurement of our deferred tax assets and liabilities is subject to the finalization of management’s analysis related to certain matters, such as developing interpretations of the provisions of the 2017 Tax Act, changes to certain estimates and amounts related to the earnings and profits of certain subsidiaries and the filing of our tax returns. U.S. Treasury regulations, administrative interpretations or court decisions interpreting the 2017 Tax Act may require further adjustments and changes in our estimates. The final determination of the Transition Toll Tax and the remeasurement of our deferred assets and liabilities will be completed as additional information becomes available, but no later than one year from the enactment of the 2017 Tax Act.

The 2017 Tax Act includes a federal statutory rate reduction from 35% to 21%, the elimination or reduction of certain domestic deductions and credits and limitations on the deductibility of interest expense and executive compensation. The 2017 Tax Act also transitions international taxation from a worldwide system to a modified territorial system and includes base erosion prevention measures on non-U.S. earnings, which has the effect of subjecting certain earnings of our foreign subsidiaries to U.S. taxation as global intangible low-taxed income. These changes are effective beginning in 2018.

At December 31, 2017, the Company had $90.3 million of deferred tax assets worldwide relating to net operating loss carryforwards, tax credit carryforwards and other temporary differences, which are available to reduce income taxes in future years. Management has considered the weight of all available evidence in determining whether a valuation allowance remains to be required against its deferred tax assets at December 31, 2017. After consideration of both positive and negative evidence, management has concluded that it is more likely than not that a substantial portion of its deferred tax assets will be realized. The positive evidence considered was three year U.S. historical cumulative profitability, projected future taxable income and length of carry-forward periods of net operating losses and tax credits. The primary negative evidence to be considered is the volatile semiconductor industry that the Company operates in. The Company has continued to maintain a $7.1 million valuation allowance in the U.S. against certain tax credits and state net operating losses due to the uncertainty of their realization based on long-term Company forecasts and the expiration dates on these attributes. If future operating results of the U.S. or these foreign jurisdictions significantly exceed expectations it is reasonably possible that there could be a further reduction in the valuation allowance in the future. Further reduction of the valuation allowance, in whole or in part, would result in a non-cash income tax benefit during the period of reduction.

At December 31, 2017, the Company has federal and state net operating loss carryforwards of $298.9 million and foreign net operating loss carryforwards of $2.9 million expiring principally between 2018 and 2034.

The Company has research and development and other tax credit carryforwards of $21.2 million at December 31, 2017 that can be used to reduce future federal and state income tax liabilities. These tax credit carryforwards expire principally between 2017 and 2037.

It is Company policy to provide taxes for the total anticipated tax impact of the undistributed earnings of our wholly-owned foreign subsidiaries, as such earnings are not expected to be reinvested indefinitely. The Company anticipates that certain state taxes resulting from remitting such earnings will be offset by net operating loss or credit carryforwards to the extent available. In addition, the Company does not anticipate incurring a foreign withholding tax on remitting such earnings since it does not intend to remit the earnings as dividends.

The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction and various states and foreign jurisdictions. The Company and most foreign subsidiaries are subject to income tax examinations by tax authorities for all years dating back to 2011. The Company’s policy is to recognize interest related to unrecognized tax benefits as interest expense and penalties as operating expenses. The Company believes that it has appropriate support for the income tax positions taken and to be taken on its tax returns and that its accruals for tax liabilities are adequate for all open years based on an assessment of many factors including past experience and interpretations of tax law applied to the facts of each matter.

At December 31, 2017, the Company had unrecognized tax benefits related to uncertain tax positions of approximately $9.1 million, of which approximately $8.0 million reduced the Company’s deferred tax assets and the offsetting valuation allowance and $1.1 million was recorded in other long-term liabilities. During the first quarter of 2017, the statute of limitations associated with two tax positions previously taken by the Company expired. The related tax reserve of $0.3 million and accrued interest of $0.2 million that had been recorded were reversed during the twelve months ended December 31, 2017. The Company recognized a benefit of $0.1 million in interest and penalties related to unrecognized tax benefits for the year-ended December 31, 2017.

A reconciliation of the beginning and ending balance of unrecognized tax benefits are as follows:


	2017		2016		2015
	(in thousands)
Balance at beginning of year	$	6,844	$	7,671	$	7,960
Increase in unrecognized tax benefits as a result of tax positions taken during a prior period		81		76		(78)
Decreases in unrecognized tax benefits related to settlements with tax authorities		—		—		(211)
Reductions to unrecognized tax benefits as a result of a lapse of the applicable statute of limitation		(511)		(903)		—
Increases in unrecognized tax benefits as a result of tax positions taken during the current period		2,691		—		—
Balance at end of year	$	9,105	$	6,844	$	7,671

Recorded as other long-term liability	$	1,109	$	1,462	$	2,142
Recorded as a decrease in deferred tax assets and offsetting valuation allowance		7,996		5,382		5,529
Balance at end of year	$	9,105	$	6,844	$	7,671

Quarterly Results of Operations (unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Results of Operations (unaudited)

Quarterly Results of Operations (unaudited)

Note 17. Quarterly Results of Operations (unaudited)


	Dec. 31,		Sept. 30,		June 30,		March 31,		Dec. 31,		Sept. 30,		June 30,		March 31,
	2017(1)		2017		2017		2017		2016		2016		2016		2016
	(in thousands, except per share data)
Revenue	$	116,396	$	104,482	$	102,790	$	86,893	$	69,358	$	65,650	$	64,451	$	67,521
Gross profit		36,720		39,751		39,062		34,714		26,947		24,104		25,131		23,415
Net income		91,680		11,841		13,932		9,506		3,965		2,151		2,937		1,948
Net income per basic share	$	2.88	$	0.38	$	0.46	$	0.32	$	0.13	$	0.07	$	0.10	$	0.07
Net income per diluted share	$	2.68	$	0.35	$	0.42	$	0.29	$	0.13	$	0.07	$	0.10	$	0.06

(1)

Gross profit includes $6.2 million charge to inventory reserves. Net income also includes an $81.6 million tax benefit relating to the reversal of a valuation allowance on deferred tax assets.

Schedule II-Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2017

Schedule II-Valuation and Qualifying Accounts

Schedule II-Valuation and Qualifying Accounts

Schedule II—Valuation and Qualifying Accounts

Axcelis Technologies, Inc.

(In thousands)


	Balance at		Charged to						Balance at
	Beginning of		Costs and						End of
	Period		Expenses		Deductions		Other(*)		Period
Year ended December 31, 2017
Allowance for doubtful accounts and returns(**)	$	77	$	—	$	(77)	$	—	$	—
Reserve for excess and obsolete inventory(***)		8,897		8,135		(2,820)		—		14,212
Year ended December 31, 2016
Allowance for doubtful accounts and returns(**)	$	—	$	106	$	(29)	$	—	$	77
Reserve for excess and obsolete inventory(***)		10,465		1,051		(2,619)		—		8,897
Year ended December 31, 2015
Allowance for doubtful accounts and returns(**)	$	390	$	—	$	(390)	$	—	$	—
Reserve for excess and obsolete inventory(***)		23,642		1,721		(14,898)		—		10,465

(*) Represents foreign currency translation adjustments.

(**) Deductions include the write-off of accounts receivable.

(***) Deductions include the disposal and sale of fully reserved inventory

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Summary of Significant Accounting Policies

Basis of Presentation

(a) Basis of Presentation

Events occurring subsequent to December 31, 2017 have been evaluated for potential recognition or disclosure in the consolidated financial statements.

Use of Estimates

(b) Use of Estimates

Foreign Currency

Cash and Cash Equivalents

(d) Cash and Cash Equivalents

Inventories

(e) Inventories

Property, Plant and Equipment

(f) Property, Plant and Equipment

Property, plant and equipment are stated at cost, less accumulated depreciation and amortization.

Depreciation and amortization are recorded using the straight‑line method over the estimated useful lives of the related assets as follows:


Asset Classification	Estimated Useful Life
Land and buildings (under lease)		Lesser of the lease term or estimated useful life of the asset
Machinery and equipment		7 to 10 years

Repairs and maintenance costs are expensed as incurred. Expenditures for renewals and betterments are capitalized.

Impairment of Long-Lived Assets

(g) Impairment of Long‑Lived Assets

The Company did not have any indicators of impairment during the period ending December 31, 2017. The Company did not record an impairment charge in the years ended December 31, 2017, 2016, or 2015.

Concentration of Risk and Off-Balance Sheet Risk

(h) Concentration of Risk and Off‑Balance Sheet Risk

The Company has no significant off‑balance‑sheet risk such as currency exchange contracts, option contracts or other hedging arrangements.

Revenue Recognition

(i) Revenue Recognition

Shipping and Handling Costs

(j) Shipping and Handling Costs

Shipping and handling costs are included in cost of revenue.

Stock-Based Compensation

(k) Stock‑Based Compensation

See Note 11 for additional information relating to stock‑based compensation.

Income Taxes

(l) Income Taxes

Computation of Net Income per Share

(m) Computation of Net Income per Share

The components of net income per share are as follows:


	Year ended December 31,
	2017		2016		2015
	(in thousands, except per share data)
Net income available to common stockholders	$	126,959	$	11,001	$	14,678
Weighted average common shares outstanding used in computing basic income per share		30,866		29,195		28,595
Incremental options and RSUs		2,570		1,752		1,634
Weighted average common shares used in computing diluted net income per share		33,436		30,947		30,229
Net income per share
Basic	$	4.11	$	0.38	$	0.51
Diluted	$	3.80	$	0.36	$	0.49

Diluted weighted average common shares outstanding does not include options and restricted stock units

outstanding to purchase 0.9 million and 0.9 million common equivalent shares for the periods ended December 31, 2016 and 2015, respectively, as their effect would have been anti-dilutive.

Accumulated Other Comprehensive Income

(n) Accumulated Other Comprehensive Income

The following table presents the changes in accumulated other comprehensive income, net of tax, by component for the year ended December 31, 2017:


	Foreign		Defined benefit
	currency		pension plan		Total
	(in thousands)
Balance at December 31, 2016	$	(1,591)	$	(688)	$	(2,279)
Other comprehensive income and pension reclassification		4,347		108		4,455
Balance at December 31, 2017	$	2,756	$	(580)	$	2,176

Recent Accounting Guidance

(o) Recent Accounting Guidance

Accounting Standards or Updates Recently Adopted

The Company has also elected to continue to estimate a forfeiture rate associated with our stock-based awards and related expense.

Accounting Standards or Updates Not Yet Effective

The Company has substantially completed the implementation of Topic 606 and has identified the necessary changes to its policies, processes, systems, and controls.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Significant Accounting Policies

Schedule of estimated useful lives of the related assets


Asset Classification	Estimated Useful Life
Land and buildings (under lease)		Lesser of the lease term or estimated useful life of the asset
Machinery and equipment		7 to 10 years

Schedule of components of net income per share


	Year ended December 31,
	2017		2016		2015
	(in thousands, except per share data)
Net income available to common stockholders	$	126,959	$	11,001	$	14,678
Weighted average common shares outstanding used in computing basic income per share		30,866		29,195		28,595
Incremental options and RSUs		2,570		1,752		1,634
Weighted average common shares used in computing diluted net income per share		33,436		30,947		30,229
Net income per share
Basic	$	4.11	$	0.38	$	0.51
Diluted	$	3.80	$	0.36	$	0.49

Schedule of changes in accumulated other comprehensive income, net of tax


	Foreign		Defined benefit
	currency		pension plan		Total
	(in thousands)
Balance at December 31, 2016	$	(1,591)	$	(688)	$	(2,279)
Other comprehensive income and pension reclassification		4,347		108		4,455
Balance at December 31, 2017	$	2,756	$	(580)	$	2,176

Cash, cash equivalents and restricted cash (Tables)

12 Months Ended

Dec. 31, 2017

Cash, cash equivalents and restricted cash

Schedule of reconciliation of cash, cash equivalents and restricted cash


	December 31,
	2017			2016
	(dollars in thousands)
Cash and cash equivalents	$	133,407	$	70,791
Short-term and long-term restricted cash		7,473		6,864
Total cash, cash equivalents and restricted cash	$	140,880	$	77,655

Accounts Receivable, net (Tables)

12 Months Ended

Dec. 31, 2017

Accounts Receivable, net

Schedule of components of accounts receivable


	December 31,
	2017		2016
	(in thousands)
Trade receivables	$	75,302	$	50,650
Allowance for doubtful accounts		—		(77)
Trade receivables, net	$	75,302	$	50,573

Inventories, net (Tables)

12 Months Ended

Dec. 31, 2017

Inventories, net

Schedule of components of inventories


	December 31,
	2017		2016
	(in thousands)
Raw materials	$	82,313	$	80,503
Work in process		31,651		14,117
Finished goods (completed systems)		6,580		19,233
Inventories, net	$	120,544	$	113,853

Property, Plant and Equipment, net (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment, net.

Schedule of components of property, plant and equipment


	December 31,
	2017		2016
	(in thousands)
Land and buildings	$	76,260	$	75,792
Machinery and equipment		11,477		9,472
Construction in process		6,982		1,704
Total cost		94,719		86,968
Accumulated depreciation		(58,551)		(56,128)
Property, plant and equipment, net	$	36,168	$	30,840

Assets Manufactured for Internal Use, net (Tables)

12 Months Ended

Dec. 31, 2017

Assets Manufactured for Internal Use, net

Schedule of components of assets manufactured for internal use


	December 31,
	2017		2016
	(in thousands)
Internal use assets	$	40,366	$	42,776
Construction in process		301		1,745
Total cost		40,667		44,521
Accumulated depreciation		(20,035)		(22,838)
Assets manufactured for internal use, net	$	20,632	$	21,683

Product Warranty (Tables)

12 Months Ended

Dec. 31, 2017

Product Warranty

Schedule of product warranty liability



	Year ended December 31,
	2017		2016		2015
	(in thousands)
Balance at January 1 (beginning of year)	$	2,666	$	3,555	$	1,526
Warranties issued during the period		5,671		3,125		4,305
Settlements made during the period		(2,603)		(4,249)		(2,672)
Changes in estimate of liability for pre-existing warranties during the period		(1,232)		235		396
Balance at December 31 (end of period)	$	4,502	$	2,666	$	3,555

Amount classified as current	$	4,112	$	2,426	$	3,363
Amount classified as long-term		390		240		192
Total warranty liability	$	4,502	$	2,666	$	3,555

Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

Employee Benefit Plans

Schedule of classification of liabilities in Consolidated Balance Sheets


	Year ended
	December 31,
	2017		2016
	(in thousands)
Current:
Accrued compensation	$	967	$	902
Total current liabilities	$	967	$	902
Long-term:
Other long-term liabilities		3,583		3,057
Total liabilities	$	4,550	$	3,959

Stock Award Plans and Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Stock Award Plans and Stock Based Compensation

Schedule of estimated weighted-average assumptions used in calculation of fair value of options granted


	Year ended December 31,
	2017	2016	2015
Weighted-average expected volatility	N/A	49.3% — 56.7%	56.2% — 64.7%
Weighted-average expected term	N/A	4.7 years	4.6 — 4.7 years
Risk-free interest rate	N/A	1.1% — 2.0%	1.3% — 1.6%
Expected dividend yield	N/A	0%	0%

Summary of stock option activity


				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
		Exercise		Contractual	Intrinsic
	Options	Price		Term	Value
	(in thousands)			(years)	(in thousands)
Outstanding at December 31, 2016	4,951	$	7.29
Granted	—		—
Exercised	(2,358)		6.58
Canceled	(15)		10.24
Expired	(2)		21.32
Outstanding at December 31, 2017	2,576	$	7.91	3.21	$	53,571
Exercisable at December 31, 2017	2,008	$	7.16	2.92	$	43,236
Options Vested or Expected to Vest at December 31, 2017(1)	2,555	$	7.88	3.25	$	53,189

Schedule of changes in the Company's non-vested restricted stock units


		Weighted-Average
		Grant Date Fair
	Shares/units	Value per Share
	(in thousands)
Outstanding at December 31, 2016	548	$	9.85
Granted	320		20.72
Vested	(196)		11.32
Forfeited	(55)		10.36
Outstanding at December 31, 2017	617	$	14.93

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Measurements

Schedule of Company's assets and liabilities by level within the fair value hierarchy


	December 31, 2017
	Fair Value Measurements
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash equivalents:
Money market funds, U.S. Government Securities and Agency Investments	$	116,433	$	—	$	—	$	116,433


	December 31, 2016
	Fair Value Measurements
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash equivalents:
Money market funds	$	54,170	$	—	$	—	$	54,170

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies

Schedule of future minimum lease commitments on non-cancelable operating leases

Future minimum lease commitments on non‑cancelable operating leases for the year ended December 31, 2017 are as follows:


	Operating
	Leases
	(in thousands)
2018	$	2,915
2019		1,836
2020		894
2021		420
2022		202
Thereafter		39
	$	6,306

Cash payment schedule associated with lease obligation

The following table relates to the cash payment schedule associated with this lease obligation as of December 31, 2017:


	Lease
	Obligation
	(in thousands)
2018	$	5,471
2019		5,594
2020		5,719
2021		5,848
2022		5,980
Thereafter		92,020
Total lease payments	$	120,632
Less interest portion		(72,918)
Sale leaseback obligation	$	47,714

Business Segment and Geographic Region Information (Tables)

12 Months Ended

Dec. 31, 2017

Business Segment and Geographic Region Information

Schedule of revenue by product lines


	Year ended December 31,
	2017		2016		2015
	(in thousands)
Ion implantation systems and services	$	391,051	$	248,885	$	282,624
Other systems and services		19,510		18,095		18,871
Total revenue	$	410,561	$	266,980	$	301,495

Schedule of revenue and long-lived assets by geographic region


			Long-Lived
	Revenue		Assets
	(in thousands)
2017
United States	$	313,916	$	56,089
Europe		26,936		—
Asia Pacific		69,709		707
	$	410,561	$	56,796
2016
United States	$	191,261	$	52,006
Europe		25,436		—
Asia Pacific		50,283		517
	$	266,980	$	52,523
2015
United States	$	226,890	$	41,729
Europe		24,209		—
Asia Pacific		50,396		334
	$	301,495	$	42,063

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes

Schedule of loss before income taxes


	Year ended December 31,
	2017		2016		2015
	(in thousands)
United States	$	40,752	$	8,880	$	12,708
Foreign		3,079		2,144		2,497
Income before income taxes	$	43,831	$	11,024	$	15,205

Schedule of provision for income taxes


	Year ended December 31,
	2017		2016		2015
	(in thousands)
Current:
United States
Federal	$	430	$	—	$	—
State		32		49		(33)
Foreign		230		(217)		374
Total current		692		(168)		341
Deferred:
Federal		(82,048)		—		—
State		(1,698)		—		—
Foreign		(74)		191		186
Total deferred		(83,820)		191		186
Income tax provision	$	(83,128)	$	23	$	527

Schedule of reconciliations of income taxes at the United States Federal statutory rate to the effective income tax rate


	Year ended December 31,
	2017		2016		2015
	(in thousands)
Income tax benefit at the United States statutory rate	$	15,341	$	3,859	$	5,322
State income taxes		203		32		(22)
Unrecognized tax benefits		(285)		(615)		(174)
Effect of change in valuation allowance		(115,831)		(7,765)		(5,676)
Foreign income tax rate differentials		(312)		233		600
Unremitted earnings of foreign subsidiaries		(8,933)		305		(102)
Stock options		(10,342)		264		379
Credit expirations		—		3,565		—
Repatriation of foreign earnings		4,556		—		—
Recognition of equity NOL's		(1,165)		—		—
Rate change		42,531		—		—
Credit generation		(8,778)		—		—
Discrete items, net		31		—		(540)
Other, net		(144)		145		740
Income tax provision	$	(83,128)	$	23	$	527

Schedule of significant components of current and long-term deferred income taxes


	Year ended December 31,
	2017		2016


Federal net operating loss carryforwards	$	56,646	$	98,007
State net operating loss carryforwards		1,586		1,546
Foreign net operating loss carryforwards		758		673
Federal tax credit carryforwards		14,312		12,778
State tax credit carryforwards		6,908		2,566
Unremitted earnings of foreign subsidiaries		(21)		(8,913)
Intangible assets		116		229
Property, plant and equipment		5,838		9,774
Accrued compensation		45		97
Inventories		3,798		5,230
Stock compensation		2,351		6,687
Warranty		980		930
Deferred revenue		187		—
Other		(3,220)		(5,578)
Deferred taxes, gross		90,284		124,026
Valuation allowance		(7,136)		(122,966)
Deferred taxes, net	$	83,148	$	1,060

Schedule of reconciliation of the beginning and ending balance of unrecognized tax benefits


	2017		2016		2015
	(in thousands)
Balance at beginning of year	$	6,844	$	7,671	$	7,960
Increase in unrecognized tax benefits as a result of tax positions taken during a prior period		81		76		(78)
Decreases in unrecognized tax benefits related to settlements with tax authorities		—		—		(211)
Reductions to unrecognized tax benefits as a result of a lapse of the applicable statute of limitation		(511)		(903)		—
Increases in unrecognized tax benefits as a result of tax positions taken during the current period		2,691		—		—
Balance at end of year	$	9,105	$	6,844	$	7,671

Recorded as other long-term liability	$	1,109	$	1,462	$	2,142
Recorded as a decrease in deferred tax assets and offsetting valuation allowance		7,996		5,382		5,529
Balance at end of year	$	9,105	$	6,844	$	7,671

Quarterly Results of Operations (unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Results of Operations (unaudited)

Schedule of quarterly results of operations

	Dec. 31,		Sept. 30,		June 30,		March 31,		Dec. 31,		Sept. 30,		June 30,		March 31,
	2017(1)		2017		2017		2017		2016		2016		2016		2016
	(in thousands, except per share data)
Revenue	$	116,396	$	104,482	$	102,790	$	86,893	$	69,358	$	65,650	$	64,451	$	67,521
Gross profit		36,720		39,751		39,062		34,714		26,947		24,104		25,131		23,415
Net income		91,680		11,841		13,932		9,506		3,965		2,151		2,937		1,948
Net income per basic share	$	2.88	$	0.38	$	0.46	$	0.32	$	0.13	$	0.07	$	0.10	$	0.07
Net income per diluted share	$	2.68	$	0.35	$	0.42	$	0.29	$	0.13	$	0.07	$	0.10	$	0.06

(1)

Gross profit includes $6.2 million charge to inventory reserves. Net income also includes an $81.6 million tax benefit relating to the reversal of a valuation allowance on deferred tax assets.

Summary of Significant Accounting Policies - Foreign Currency (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign Currency
Foreign exchange losses (gains) realized	$ 1.1	$ (0.6)	$ 0.0

Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Impairment of Long-Lived Assets
Impairment of long-lived assets		$ 0.0	$ 0.0	$ 0.0
Machinery and equipment \| Minimum
Property, plant and equipment
Useful life		7 years
Machinery and equipment \| Maximum
Property, plant and equipment
Useful life		10 years
Beverly Property Owner LLC \| Sale leaseback obligation \| Land and buildings
Property, plant and equipment
Lease term	22 years

Summary of Significant Accounting Policies - Concentration of Risk (Details) - customer	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue \| Customer concentration risk
Concentration of risk
Number of customers	2	1	2
Revenue \| Customer concentration risk \| Ten largest customers
Concentration of risk
Number of customers	10	10	10
Percentage of concentration risk	73.30%	70.20%	76.80%
Revenue \| Customer concentration risk \| One customer
Concentration of risk
Percentage of concentration risk	24.90%	17.00%	29.30%
Revenue \| Customer concentration risk \| Second customer
Concentration of risk
Percentage of concentration risk	13.10%		10.50%
Consolidated accounts receivable \| Credit concentration risk
Concentration of risk
Number of customers	3	4
Consolidated accounts receivable \| Credit concentration risk \| One customer
Concentration of risk
Percentage of concentration risk	19.80%	22.00%
Consolidated accounts receivable \| Credit concentration risk \| Second customer
Concentration of risk
Percentage of concentration risk	11.80%	12.30%
Consolidated accounts receivable \| Credit concentration risk \| Third customer
Concentration of risk
Percentage of concentration risk	10.60%	12.00%
Consolidated accounts receivable \| Credit concentration risk \| Fourth customer
Concentration of risk
Percentage of concentration risk		10.60%

Summary of Significant Accounting Policies - Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue recognition
Maximum deferral period from shipment for recognition of systems revenue and related costs									12 months
Anti-dilutive common equivalent shares excluded from calculation										900	900
Net income per share:
Net income available to common stockholders	$ 91,680	$ 11,841	$ 13,932	$ 9,506	$ 3,965	$ 2,151	$ 2,937	$ 1,948	$ 126,959	$ 11,001	$ 14,678
Weighted average common shares outstanding used in computing basic income per share									30,866	29,195	28,595
Weighted average common shares used in computing diluted net income per share									33,436	30,947	30,229
Net income per share
Basic	$ 2.88	$ 0.38	$ 0.46	$ 0.32	$ 0.13	$ 0.07	$ 0.10	$ 0.07	$ 4.11	$ 0.38	$ 0.51
Diluted	$ 2.68	$ 0.35	$ 0.42	$ 0.29	$ 0.13	$ 0.07	$ 0.10	$ 0.06	$ 3.80	$ 0.36	$ 0.49
Restricted Stock
Net income per share:
Incremental options and RSUs									2,570	1,752	1,634

Summary of Significant Accounting Policies - Accumulated Other Comprehensive Income (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Changes in accumulated other comprehensive income, net of tax
Balance at December 31, 2016	$ (2,279)
Other comprehensive income and pension reclassification	4,455
Balance at December 31, 2017	2,176
Foreign currency
Changes in accumulated other comprehensive income, net of tax
Balance at December 31, 2016	(1,591)
Other comprehensive income and pension reclassification	4,347
Balance at December 31, 2017	2,756
Defined benefit pension plan
Changes in accumulated other comprehensive income, net of tax
Balance at December 31, 2016	(688)
Other comprehensive income and pension reclassification	108
Balance at December 31, 2017	$ (580)

Summary of Significant Accounting Policies - Recent Accounting Guidance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2017
Recent Accounting Guidance
Tax deductions in excess of recognized compensation cost	$ 29,500
Cash, cash equivalents and restricted cash balances	7,473	$ 6,864
Effect of Change
Recent Accounting Guidance
Increase to retained earnings	1,600
ASU No. 2016-09
Recent Accounting Guidance
Tax deductions in excess of recognized compensation cost	29,500
Excess tax benefits of deferred tax assets	10,300
Reduction in net cash provided by financing activities	$ 1,200	$ 11	$ 8
ASU No. 2016-18
Recent Accounting Guidance
Cash, cash equivalents and restricted cash balances				$ 6,900

- Definition

Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

+ References + Details

Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and cash equivalents	$ 133,407	$ 70,791
Short-term and long-term restricted cash	7,473	6,864
Total cash, cash equivalents and restricted cash	140,880	$ 77,655	$ 85,825	$ 31,578
Letter of credit related to workers' compensation insurance	800
Letter of credit associated with a bank guarantee	700
Deposit related to customs activity	100
Revolving credit facility
Restricted cash which relates to support of outstanding letters of credit	7,500
Revolving credit facility \| Sale leaseback obligation
Letter of credit associated with security deposit for leaseback transaction	$ 5,900

Accounts Receivable, net (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable, net
Trade receivables	$ 75,302	$ 50,650
Allowance for doubtful accounts		(77)
Trade receivable, net	$ 75,302	$ 50,573

Inventories, net (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventories, net
Raw materials	$ 82,313	$ 80,503
Work in process	31,651	14,117
Finished goods (completed systems)	6,580	19,233
Inventories, net	$ 120,544	$ 113,853

Inventories, net - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Inventories, net additional information
Inventory Write-down	$ 6.2	$ 6.2
Charges to cost of sales due to lower of cost or market value		8.1	$ 0.8	$ 0.5
Inventory on consignment at customer locations	3.6	3.6	3.4
Inventory reserves
Inventories, net additional information
Increase in inventory reserves		5.3
Inventory reserves	$ 14.2	$ 14.2	$ 8.8

Property, Plant and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, plant and equipment
Gross	$ 94,719	$ 86,968
Accumulated depreciation	(58,551)	(56,128)
Net	36,168	30,840
Depreciation expense	2,200	1,800	$ 2,400
Land and buildings
Property, plant and equipment
Gross	76,260	75,792
Machinery and equipment
Property, plant and equipment
Gross	11,477	9,472
Construction in process
Property, plant and equipment
Gross	$ 6,982	$ 1,704

Assets Manufactured for Internal Use, net - Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets manufactured for internal use
Cost	$ 94,719	$ 86,968
Accumulated depreciation	(58,551)	(56,128)
Net	36,168	30,840
Depreciation expense	2,200	1,800	$ 2,400
Assets Manufactured for Internal Use
Assets manufactured for internal use
Cost	40,667	44,521
Accumulated depreciation	(20,035)	(22,838)
Net	20,632	21,683
Depreciation expense	2,800	2,400	$ 2,500
Assets Manufactured for Internal Use \| Internal use assets
Assets manufactured for internal use
Cost	40,366	42,776
Assets Manufactured for Internal Use \| Construction in process.
Assets manufactured for internal use
Cost	$ 301	$ 1,745

Product Warranty (Details) - USD ($) $ in Thousands	12 Months Ended
Product Warranty (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product Warranty
Product warranty period	1 year
Changes in standard product warranty liability
Balance at January 1 (beginning of year)	$ 2,666	$ 3,555	$ 1,526
Warranties issued during the period	5,671	3,125	4,305
Settlements made during the period	(2,603)	(4,249)	(2,672)
Changes in estimate of liability for pre-existing warranties during the period	(1,232)	235	396
Balance at December 31 (end of period)	4,502	2,666	3,555
Product warranty classification
Amount classified as current				$ 4,112	$ 2,426	$ 3,363
Amount classified as long-term				390	240	192
Total warranty liability	$ 2,666	$ 3,555	$ 1,526	$ 4,502	$ 2,666	$ 3,555

Financing Arrangements (Details) - USD ($) $ in Thousands	Jan. 30, 2015	Dec. 31, 2017	Dec. 31, 2016
Financing Arrangements
Sale leaseback obligation		$ 47,714	$ 47,586
Beverly Property Owner LLC \| Sale leaseback obligation \| Land and buildings
Financing Arrangements
Purchase price	$ 48,900
Lease term	22 years
Sale leaseback obligation		$ 47,700
Security deposit	$ 5,900

Employee Benefit Plans - Defined Contribution Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plan
Employer contributed by eligible participants	50.00%	50.00%
Pre-tax compensation contributed	6.00%
Defined contribution plan expenses	$ 500	$ 400	$ 400
Maximum
Defined Contribution Plan
Defined Contribution Plan, Employer Discretionary Contribution Amount		$ 1,200	$ 1
Regular employees
Defined Contribution Plan
Maximum contribution per employee under the Axcelis Long-Term Investment Plan (as a percent)	35.00%
Highly compensated employees
Defined Contribution Plan
Maximum contribution per employee under the Axcelis Long-Term Investment Plan (as a percent)	16.00%

Employee Benefit Plans - Other Compensation Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Classification of liabilities in the Consolidated Balance Sheets
Current liabilities	$ 967	$ 902
Total liabilities	4,550	3,959
Plan expenses	1,000	800	$ 700
Accrued compensation
Classification of liabilities in the Consolidated Balance Sheets
Current liabilities	967	902
Other long-term liabilities
Classification of liabilities in the Consolidated Balance Sheets
Long-term liabilities	$ 3,583	$ 3,057

Stock Award Plans and Stock Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended			68 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	May 02, 2012
Stock-based compensation
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001		$ 0.001
Stock-Based Compensation Expense
Forfeiture rate (as a percent)	5.00%	5.00%	5.00%
Stock-based compensation expense	$ 5,700	$ 5,200	$ 5,600
Tax deductions in excess of recognized compensation cost	29,500
Tax benefit	$ 10,300
Employee stock purchase plan
Stock-based compensation
Number of shares of common stock available for future grant	300,000			300,000
Employee Stock Purchase Plan
Purchase price as a percentage of the market value of a common stock on the day the stock is purchased	85.00%
Offering period over which compensation expense is amortized	6 months
Stock-Based Compensation Expense
Stock-based compensation expense	$ 100	$ 100	$ 100
Employee stock purchase plan \| Maximum
Employee Stock Purchase Plan
Payroll deductions as a percentage of employee's salary	10.00%
Number of shares purchased under the plan	100,000	100,000	100,000
Restricted stock and restricted stock units
Shares/units
Outstanding at the beginning of the period (in shares)	548,000
Granted (in shares)	320,000
Vested (in shares)	(196,000)
Forfeited (in shares)	(55,000)
Outstanding at the end of the period (in shares)	617,000	548,000		617,000
Weighted-Average Grant Date Fair Value per Share
Outstanding at the beginning of the period (in dollars per share)	$ 9.85
Granted (in dollars per share)	20.72	$ 9.73	$ 12.12
Vested (in dollars per share)	11.32
Forfeited (in dollars per share)	10.36
Outstanding at the end of the period (in dollars per share)	$ 14.93	$ 9.85		$ 14.93
Stock Options
Options
Outstanding at the beginning of the period (in shares)	4,951,000
Exercised (in shares)	(2,358,000)
Canceled (in shares)	(15,000)
Expired (in shares)	(2,000)
Outstanding at the end of the period (in shares)	2,576,000	4,951,000		2,576,000
Exercisable (in shares)	2,008,000			2,008,000
Options Vested or Expected to Vest at the end of the period (in shares)	2,555,000			2,555,000
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 7.29
Exercised (in dollars per share)	6.58
Canceled (in dollars per share)	10.24
Expired (in dollars per share)	21.32
Outstanding at the end of the period (in dollars per share)	7.91	$ 7.29		$ 7.91
Exercisable at the end of the period (in dollars per share)	7.16			7.16
Options Vested or Expected to Vest at the end of the period (in dollars per share)	$ 7.88			$ 7.88
Weighted Average Remaining Contractual Term
Outstanding at the end of the period	3 years 2 months 16 days
Exercisable at the end of the period	2 years 11 months 1 day
Options Vested or Expected to Vest at the end of the period	3 years 3 months
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars)	$ 53,571			$ 53,571
Exercisable at the end of the period (in dollars)	43,236			43,236
Options Vested or Expected to Vest at the end of the period (in dollars)	53,189			53,189
Additional disclosure
Total intrinsic value of options exercised (in dollars)	39,700	$ 2,500	$ 5,300
Total fair value of stock options vested (in dollars)	3,100	$ 3,900	$ 5,400
Weighted average grant fair value of options granted (in dollars per share)		$ 5.75	$ 5.05
Total forfeiture adjusted unrecognized compensation cost (in dollars)	$ 2,300			$ 2,300
Weighted-average period over which unrecognized compensation cost is expected to be recognized	1 year 4 months 24 days
Stock Options \| Employees
Stock-based compensation
Vesting period	4 years
Period after termination to exercise awards that were vested	90 days
Period after termination to retiring employees to exercise vested awards	1 year
Stock Options \| Non-employee members of Board of Directors
Stock-based compensation
Vesting period	6 months
Restricted Stock
Shares/units
Granted (in shares)	0	0	0
Vested (in shares)	0	0	0
Stock Options and Restricted Stock Units
Estimated weighted-average assumptions
Weighted-average expected term		4 years 8 months 12 days
Risk-free interest rate, minimum (as a percent)		1.10%	1.30%
Risk-free interest rate, maximum (as a percent)		2.00%	1.60%
Expected dividend yield (as a percent)		0.00%	0.00%
Stock Options and Restricted Stock Units \| Minimum
Estimated weighted-average assumptions
Weighted-average expected volatility (as a percent)		49.30%	56.20%
Weighted-average expected term			4 years 7 months 6 days
Stock Options and Restricted Stock Units \| Maximum
Estimated weighted-average assumptions
Weighted-average expected volatility (as a percent)		56.70%	64.70%
Weighted-average expected term			4 years 8 months 12 days
2000 Stock Plan
Stock-based compensation
Awards granted (in shares)				0
Number of shares of common stock available for future grant	0			0
2000 Stock Plan \| Stock Options
Stock-based compensation
Expiration period	10 years
2012 Equity Incentive Plan
Stock-based compensation
Number of shares of common stock originally reserved for future grant					6,500,000
Common stock, par value (in dollars per share)					$ 0.001
Number of shares of common stock available for future grant	1,300,000			1,300,000
2012 Equity Incentive Plan \| Stock Options
Stock-based compensation
Expiration period	7 years
2012 Equity Incentive Plan \| Restricted Stock
Shares/units
Granted (in shares)	0	0	0
2012 Equity Incentive Plan \| Stock Options and Restricted Stock Units
Estimated weighted-average assumptions
Weighted-average expected term	7 years

Stockholders' Equity (Details) - shares shares in Thousands	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity
Number of common stock authorized	75,000	75,000
Number of common stock outstanding	32,048	29,518

Fair Value Measurements (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Money market funds \| Total
Fair Value Measurements
Money market funds		$ 54,170
Money market funds, US Government Securities and Agency Investments \| Total
Fair Value Measurements
Money market funds	$ 116,433
Level 1 \| Money market funds
Fair Value Measurements
Money market funds		$ 54,170
Level 1 \| Money market funds, US Government Securities and Agency Investments
Fair Value Measurements
Money market funds	$ 116,433

Commitments and Contingencies (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Lease Commitments
Rental expense under operating leases		$ 3,900	$ 3,800	$ 3,800
Future minimum lease commitments on non-cancelable operating leases
2018		2,915
2019		1,836
2020		894
2021		420
2022		202
Thereafter		39
Total		6,306
Cash payment schedule associated with lease obligation
2018		5,471
2019		5,594
2020		5,719
2021		5,848
2022		5,980
Thereafter		92,020
Total lease payments		120,632
Less interest portion		(72,918)
Sales leaseback obligation		47,714	$ 47,586
Purchase Commitments
Non-cancelable contracts and purchase orders for inventory		83,500
Sale leaseback obligation \| Land and buildings \| Beverly Property Owner LLC
Cash payment schedule associated with lease obligation
Sales leaseback obligation		$ 47,700
Purchase Commitments
Lease term	22 years

Business Segment and Geographic Region Information - Number of Segments (Details)	12 Months Ended
	Dec. 31, 2017 segment
Business Segment and Geographic Region Information
Number of business segments	1

Business Segment and Geographic Region Information - Revenue by Product Line (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue by product lines
Revenue	$ 116,396	$ 104,482	$ 102,790	$ 86,893	$ 69,358	$ 65,650	$ 64,451	$ 67,521	$ 410,561	$ 266,980	$ 301,495
Ion implantation systems services
Revenue by product lines
Revenue									391,051	248,885	282,624
Other systems and services
Revenue by product lines
Revenue									$ 19,510	$ 18,095	$ 18,871

Business Segment and Geographic Region Information - Revenue and Long-Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue and long-lived assets by geographic region
Revenue	$ 116,396	$ 104,482	$ 102,790	$ 86,893	$ 69,358	$ 65,650	$ 64,451	$ 67,521	$ 410,561	$ 266,980	$ 301,495
Long-Lived Assets	56,796				52,523				56,796	52,523	42,063
United States.
Revenue and long-lived assets by geographic region
Revenue									313,916	191,261	226,890
Long-Lived Assets	56,089				52,006				56,089	52,006	41,729
Europe
Revenue and long-lived assets by geographic region
Revenue									26,936	25,436	24,209
Asia Pacific
Revenue and long-lived assets by geographic region
Revenue									69,709	50,283	50,396
Long-Lived Assets	$ 707				$ 517				707	517	334
International \| Revenue \| Geographic concentration risk
Revenue and long-lived assets by geographic region
Revenue									$ 348,500	$ 213,800	$ 256,500
Percentage of revenue									84.90%	80.00%	85.10%

Income Taxes - Tax Effects (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income (loss) before income taxes
United States	$ 40,752	$ 8,880	$ 12,708
Foreign	3,079	2,144	2,497
Income before income taxes	43,831	11,024	15,205
Current:
Federal	430
State	32	49	(33)
Foreign	230	(217)	374
Total current	692	(168)	341
Deferred:
Federal	(82,048)
State	(1,698)
Foreign	(74)	191	186
Total deferred	(83,820)	191	186
Income tax provision	(83,128)	23	527
Reconciliations of income taxes at the United States Federal statutory rate to the effective income tax rate
Income tax benefit at the United States statutory rate	15,341	3,859	5,322
State income taxes	203	32	(22)
Unrecognized tax benefits	(285)	(615)	(174)
Effect of change in valuation allowance	(115,831)	(7,765)	(5,676)
Foreign income tax rate differentials	(312)	233	600
Unremitted earnings of foreign subsidiaries	(8,933)	305	(102)
Stock options	(10,342)	264	379
Credit expirations		3,565
Repatriation of foreign earnings	4,556
Recognition of equity NOL's	(1,165)
Rate change	42,531
Credit generation	(8,778)
Discrete items, net	31		(540)
Other, net	(144)	145	740
Income tax provision	(83,128)	23	$ 527
Significant components of long-term deferred income taxes
Federal net operating loss carryforwards	56,646	98,007
State net operating loss carryforwards	1,586	1,546
Foreign net operating loss carryforwards	758	673
Federal tax credit carryforwards	14,312	12,778
State tax credit carryforwards	6,908	2,566
Unremitted earnings of foreign subsidiaries	(21)	(8,913)
Intangible assets	116	229
Property, plant and equipment	5,838	9,774
Accrued compensation	45	97
Inventories	3,798	5,230
Stock compensation	2,351	6,687
Warranty	980	930
Deferred revenue	187
Other	(3,220)	(5,578)
Deferred taxes, gross	90,284	124,026
Valuation allowance	(7,136)	(122,966)
Deferred taxes, net	$ 83,148	$ 1,060

Income Taxes - Tax Cuts and Jobs Act (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Percentage of tax on earnings in the form of cash and cash equivalents		15.50%
Percentage of tax on earnings other than in the form of cash and cash equivalents		8.00%
Accrued income tax liabilities under the transition toll tax		$ 400
Transition toll tax, period		8 years
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%
Deferred taxes, net		$ 83,148	$ 1,060
Forecast
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%

Income Taxes - Operating Loss Carryforwards (Details) $ in Millions	Dec. 31, 2017 USD ($)
Federal and state
Operating loss carryforwards
Net operating loss carryforwards	$ 298.9
Foreign
Operating loss carryforwards
Net operating loss carryforwards	$ 2.9

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
Reversal of tax reserve	$ 511	$ 903
Interest and penalty expense recognized related to unrecognized tax benefits	100
Tax Reserve Member
Tax Credit Carryforward [Line Items]
Reversal of tax reserve	300
Unrecognized Tax Benefits Reserve Accrued Interest Member
Tax Credit Carryforward [Line Items]
Reversal of tax reserve	200
Research and development and other tax credit carryforwards
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 21,200

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of the beginning and ending balance of unrecognized tax benefits
Balance at beginning of year	$ 6,844	$ 7,671	$ 7,960
Increase in unrecognized tax benefits as a result of tax positions taken during a prior period	81	76
Increase in unrecognized tax benefits as a result of tax positions taken during a prior period			(78)
Decreases in unrecognized tax benefits related to settlements with tax authorities			(211)
Reductions to unrecognized tax benefits as a result of a lapse of the applicable statute of limitations	(511)	(903)
Increases in unrecognized tax benefits as a result of tax positions taken during the current period	2,691
Balance at end of year	9,105	6,844	7,671
Recorded as other long-term liability				$ 1,109	$ 1,462	$ 2,142
Recorded as a decrease in deferred tax assets and offsetting valuation allowance				7,996	5,382	5,529
Unrecognized tax benefits	$ 6,844	$ 7,671	$ 7,960	$ 9,105	$ 6,844	$ 7,671

Quarterly Results of Operations (unaudited) - Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Results of Operations (unaudited)
Revenue	$ 116,396	$ 104,482	$ 102,790	$ 86,893	$ 69,358	$ 65,650	$ 64,451	$ 67,521	$ 410,561	$ 266,980	$ 301,495
Gross profit	36,720	39,751	39,062	34,714	26,947	24,104	25,131	23,415	150,247	99,598	101,706
Net income	$ 91,680	$ 11,841	$ 13,932	$ 9,506	$ 3,965	$ 2,151	$ 2,937	$ 1,948	$ 126,959	$ 11,001	$ 14,678
Net income per basic share (in dollars per share)	$ 2.88	$ 0.38	$ 0.46	$ 0.32	$ 0.13	$ 0.07	$ 0.10	$ 0.07	$ 4.11	$ 0.38	$ 0.51
Net income per diluted share (in dollars per share)	$ 2.68	$ 0.35	$ 0.42	$ 0.29	$ 0.13	$ 0.07	$ 0.10	$ 0.06	$ 3.80	$ 0.36	$ 0.49

Quarterly Results of Operations (unaudited) - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017
Quarterly Results of Operations (unaudited)
Inventory Write-down	$ 6.2	$ 6.2
Tax benefit relating to reversal of a valuation allowance on deferred tax assets	$ 81.6

Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts and returns
Changes in Valuation and Qualifying Accounts
Balance at Beginning of Period	$ 77		$ 390
Charged to Costs and Expenses		$ 106
Deductions	(77)	(29)	(390)
Balance at End of Period		77
Inventory reserves
Changes in Valuation and Qualifying Accounts
Balance at Beginning of Period	8,897	10,465	23,642
Charged to Costs and Expenses	8,135	1,051	1,721
Deductions	(2,820)	(2,619)	(14,898)
Balance at End of Period	$ 14,212	$ 8,897	$ 10,465