Onto Innovation (ONTO) 10-Q 3 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	NANOMETRICS INC
Entity Central Index Key	704,532
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	NANO
Current Fiscal Year End Date	--12-30
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		25,594,642

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 44,041	$ 47,062
Marketable securities	96,316	82,899
Accounts receivable, net of allowances of $69 and $73, respectively	41,261	39,457
Inventories	55,020	38,837
Inventories-delivered systems	3,320	2,457
Prepaid expenses and other	9,910	5,667
Total current assets	249,868	216,379
Property, plant and equipment, net	42,317	44,226
Goodwill	10,099	8,940
Intangible assets, net	2,258	412
Deferred income tax assets	16,472	17,399
Other assets	389	474
Total assets	321,403	287,830
Current liabilities:
Accounts payable	17,180	11,342
Accrued payroll and related expenses	10,260	12,656
Deferred revenue	7,229	9,168
Other current liabilities	7,704	8,047
Income taxes payable	1,689	813
Total current liabilities	44,062	42,026
Deferred revenue	1,551	816
Income taxes payable	907	841
Deferred tax liability	21	20
Other long-term liabilities	377	353
Total liabilities	46,918	44,056
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.001 par value; 3,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.001 par value, 47,000,000 shares authorized: 25,567,220 and 25,070,889, respectively, issued and outstanding	26	25
Additional paid-in capital	278,722	271,969
Accumulated deficit	(1,685)	(22,174)
Accumulated other comprehensive income (loss)	(2,578)	(6,046)
Total stockholders’ equity	274,485	243,774
Total liabilities and stockholders’ equity	$ 321,403	$ 287,830

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Allowances for doubtful accounts	$ 69	$ 73
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	3,000,000	3,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	47,000,000	47,000,000
Common stock, shares issued	25,567,220	25,070,889
Common stock, shares outstanding	25,567,220	25,070,889

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Net revenues:
Products	$ 45,571	$ 49,631	$ 147,322	$ 136,290
Service	11,104	9,083	33,094	25,680
Total net revenues	56,675	58,714	180,416	161,970
Costs of net revenues:
Cost of products	21,349	22,810	72,164	62,625
Cost of service	4,614	5,066	15,368	14,714
Amortization of intangible assets	52	434	156	1,311
Total costs of net revenues	26,015	28,310	87,688	78,650
Gross profit	30,660	30,404	92,728	83,320
Operating expenses:
Research and development	8,825	7,868	26,658	23,447
Selling	7,553	7,495	22,730	22,567
General and administrative	6,798	5,975	19,696	17,150
Amortization of intangible assets	0	0	0	24
Total operating expenses	23,176	21,338	69,084	63,188
Income from operations	7,484	9,066	23,644	20,132
Other income (expense):
Interest income	2	12	6	33
Interest expense	(25)	(92)	(84)	(276)
Other income, net	59	229	330	60
Total other income (expense), net	36	149	252	(183)
Income before income taxes	7,520	9,215	23,896	19,949
Provision for income taxes	1,756	1,332	4,492	2,568
Net income	$ 5,764	$ 7,883	$ 19,404	$ 17,381
Net income per share:
Basic (in dollars per share)	$ 0.23	$ 0.32	$ 0.77	$ 0.71
Diluted (in dollars per share)	$ 0.22	$ 0.31	$ 0.75	$ 0.70
Weighted average shares used in per share calculation:
Basic (in shares)	25,494	24,826	25,320	24,550
Diluted (in shares)	25,932	25,282	25,933	24,979

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 5,764	$ 7,883	$ 19,404	$ 17,381
Other comprehensive income (loss):
Change in foreign currency translation adjustment	764	519	3,470	2,018
Net change on unrealized gains (losses) on available-for-sale investments	15	1	(2)	73
Other comprehensive income:	779	520	3,468	2,091
Comprehensive income	$ 6,543	$ 8,403	$ 22,872	$ 19,472

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016
Cash flows from operating activities:
Net income	$ 19,404	$ 17,381
Reconciliation of net income to net cash provided by operating activities:
Depreciation and amortization	5,219	6,440
Stock-based compensation	6,775	5,432
Disposal of fixed assets	98	162
Inventory write-down	1,412	1,451
Deferred income taxes	2,153	(14)
Changes in fair value of contingent payments to Zygo Corporation		158
Changes in assets and liabilities:
Accounts receivable	1,418	(986)
Inventories	(16,828)	6,652
Inventories-delivered systems	(864)	(1,560)
Prepaid expenses and other	(3,850)	889
Accounts payable, accrued and other liabilities	709	(4,310)
Deferred revenue	(1,204)	3,825
Income taxes payable	942	(1,419)
Net cash provided by operating activities	15,384	34,101
Cash flows from investing activities:
Payments to acquire certain assets	(2,000)
Sales of marketable securities	28,624	2,093
Maturities of marketable securities	62,923	25,461
Purchases of marketable securities	(104,984)	(63,840)
Purchases of property, plant and equipment	(2,342)	(3,349)
Net cash used in investing activities	(17,779)	(39,635)
Cash flows from financing activities:
Payments to Zygo Corporation related to acquisition		(315)
Proceeds from sale of shares under employee stock option plans and purchase plan	3,678	5,984
Taxes paid on net issuance of stock awards	(3,838)	(1,578)
Net cash provided by (used in) financing activities	(160)	4,091
Effect of exchange rate changes on cash and cash equivalents	(466)	710
Net decrease in cash and cash equivalents	(3,021)	(733)
Cash and cash equivalents, beginning of period	47,062	38,154
Cash and cash equivalents, end of period	44,041	37,421
Supplemental disclosure of non-cash investing activities:
Transfer of inventory to property, plant and equipment, net		$ 1,208
Transfer of property, plant and equipment to inventory, net	$ 205

Nature of Business and Basis of

Nature of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Note 1. Nature of Business and Basis of Presentation Description of Business – Nanometrics Incorporated (“Nanometrics” or the “Company”) and its wholly-owned subsidiaries design, manufacture, market, sell and support optical critical dimension (“OCD”), thin film and overlay dimension metrology and inspection systems used primarily in the manufacturing of semiconductors, solar photovoltaics (“solar PV”) and high-brightness LEDs (“HB-LED”), as well as by customers in the silicon wafer and data storage industries. Nanometrics’ metrology systems precisely measure a wide range of film types deposited on substrates during manufacturing to control manufacturing processes and increase production yields in the fabrication of integrated circuits. The Company’s OCD technology is a patented critical dimension measurement technology that is used to precisely determine the dimensions on the semiconductor wafer that directly control the resulting performance of the integrated circuit devices. The thin film metrology systems use a broad spectrum of wavelengths, high-sensitivity optics, proprietary software, and patented technology to measure the thickness and uniformity of films deposited on silicon and other substrates as well as their chemical composition. The overlay metrology systems are used to measure the overlay accuracy of successive layers of semiconductor patterns on wafers in the photolithography process. Nanometrics’ inspection systems are used to find defects on patterned and unpatterned wafers at nearly every stage of the semiconductor production flow. The corporate headquarters of Nanometrics is located in Milpitas, California. Basis of Presentation – The accompanying condensed consolidated financial statements (“financial statements”) have been prepared on a consistent basis with the audited consolidated financial statements as of December 31, 2016, and include all normal recurring adjustments necessary to fairly state the information set forth therein. All significant intercompany accounts and transactions have been eliminated in consolidation. The financial statements have been prepared in accordance with the regulations of the United States Securities and Exchange Commission (“SEC”) for interim periods in accordance with S-X Article 10, and, therefore, omit certain information and footnote disclosure necessary to present the statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The operating results for interim periods are not necessarily indicative of the operating results that may be expected for the entire year. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the fiscal year ended December 31, 2016, which were included in the Company’s Annual Report on Form 10-K filed with the SEC on March 3, 2017. Fiscal Period – The Company uses a 52/53 week fiscal year ending on the last Saturday of the calendar year. All references to the quarter refer to Nanometrics’ fiscal quarter. The fiscal quarters reported herein are 13 week periods. Use of Estimates – The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reported period. Actual results could differ materially from those estimates. Estimates are used for, but not limited to, revenue recognition, the provision for doubtful accounts, the provision for excess, obsolete, or slow-moving inventories, valuation of intangible and long-lived assets, warranty accruals, income taxes, valuation of stock-based compensation, and contingencies. Revenue Recognition – The Company derives revenue from the sale of process control metrology and inspection systems and related upgrades (“product revenue”) as well as spare part sales, billable service and service contracts (together “service revenue”). Upgrades are system software and hardware performance upgrades that extend the features and functionality of a product. Upgrades are included in product revenue, which consists of sales of complete, advanced process control metrology and inspection systems (the “system(s)”). Nanometrics’ systems consist of hardware and software components that function together to deliver the essential functionality of the system. Arrangements for sales of systems and upgrades often include defined customer-specified acceptance criteria. In summary, the Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the seller's price is fixed or determinable, and collectability is reasonably assured. For repeat product sales to existing customers, revenue recognition occurs at the time title and risk of loss transfer to the customer, which usually occurs upon shipment from the Company's manufacturing location, if it can be reliably demonstrated that the product has successfully met the defined customer specified acceptance criteria and all other recognition criteria have been met. For initial sales where the product has not previously met the defined customer specified acceptance criteria, product revenues are recognized upon the earlier of receipt of written customer acceptance or expiration of the contractual acceptance period. In Japan, where contractual terms with the customer specify risk of loss and title transfers upon customer acceptance, revenue is recognized upon receipt of written customer acceptance, provided that all other recognition criteria have been met. The Company warrants its products against defects in manufacturing. Upon recognition of product revenue, a liability is recorded for anticipated warranty costs. On occasion, customers request a warranty period longer than the Company's standard warranty. In those instances, where extended warranty services are separately quoted to the customer, the associated revenue is deferred and recognized as service revenue ratably over the term of the extended warranty period. The portion of service contracts and extended warranty services agreements that are uncompleted at the end of any reporting period are included in deferred revenue. The Company sells software that is considered to be an upgrade to a customer's existing systems. These standalone software upgrades are not essential to the tangible product's functionality and are accounted for under software revenue recognition rules which require vendor specific objective evidence (“VSOE”) of fair value to allocate revenue in a multiple element arrangement. Revenue from software sales is recognized when the software is delivered to the customer, provided that all other recognition criteria have been met. The majority of other upgrades are sold based on published specifications. For basic upgrades, revenue is recognized at the time title and risk of loss transfer to the customer which is usually upon shipment. For complex and extensive upgrades, specific acceptance or prior acceptance for a similar upgrade is required in order to recognize revenue. Revenue related to spare parts is recognized upon shipment. Revenue related to billable services is recognized as the services are performed. Service contracts may be purchased by the customer during or after the warranty period and revenue is recognized ratably over the service contract period. Frequently, the Company delivers products and various services in a single transaction. The Company's deliverables consist of tools, installation, upgrades, billable services, spare parts, and service contracts. The Company's typical multi-element arrangements include a sale of one or multiple tools that include installation and standard warranty. Other arrangements consist of a sale of tools bundled with service elements or delivery of different types of services. The Company's tools, upgrades, and spare parts are generally delivered to customers within a period of up to six months from order date. Installation is usually performed soon after delivery of the tool. The portion of revenue associated with installation is deferred based on relative selling price and that revenue is recognized upon completion of the installation and receipt of final acceptance. Billable services are billed on a time and materials basis and performed as requested by customers. Under service contract arrangements, services are provided as needed over the fixed arrangement term, which terms can be up to twelve months. The Company does not grant its customers a general right of return or any refund terms and imposes a penalty on orders cancelled prior to the scheduled shipment date. The Company evaluates its revenue arrangements to identify deliverables and to determine whether these deliverables are separable into multiple units of accounting. The Company allocates the arrangement consideration among the deliverables based on relative selling prices. The Company has established VSOE for some of its products and services when a substantial majority of selling prices falls within a narrow range when sold separately. For deliverables with no established VSOE, the Company uses best estimate of selling price to determine standalone selling price for such deliverable. The Company does not use third party evidence to determine standalone selling price since this information is not widely available in the market as the Company's products contain a significant element of proprietary technology and the solutions offered differ substantially from competitors. The Company has established a process for developing estimated selling prices, which incorporates historical selling prices, the effect of market conditions, gross margin objectives, pricing practices, as well as entity-specific factors. The Company monitors and evaluates estimated selling price on a regular basis to ensure that changes in circumstances are accounted for in a timely manner. When certain elements in multiple-element arrangements are not delivered, or accepted at the end of a reporting period, the relative selling prices of undelivered elements are deferred until these elements are delivered and/or accepted. If deliverables cannot be accounted for as separate units of accounting, the entire arrangement is accounted for as a single unit of accounting and revenue is deferred until all elements are delivered and all revenue recognition requirements are met.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2017
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	Note 2. Recent Accounting Pronouncements Accounting Standards Adopted In March 2016, the FASB issued an accounting standards update that simplifies several aspects of the accounting for share-based payment award transactions, including income tax consequences, classification of awards as equity or liability, and classification on the statement of cash flows. The new standard requires adoption of certain amendments relevant to the Company to be applied using a modified retrospective transition method by means of cumulative effect adjustment to retained earnings as of the beginning of the fiscal year 2017. The new standard permits entities to make an accounting policy election related to how forfeitures will impact the recognition of compensation cost for stock-based compensation. The Company has elected to account for forfeitures as they occur and adopted this change on a modified retrospective basis. The cumulative effect of this change resulted in a $0.1 million increase to accumulated deficit as of January 1, 2017. Furthermore, the standard requires excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled rather than paid-in capital. The Company recorded the cumulative effect of this change as a $1.2 million reduction to accumulated deficit in the first quarter of fiscal 2017 to reflect the recognition of excess tax benefits in prior years, with a corresponding adjustment to deferred tax assets and long-term tax liabilities. The Company adopted the guidance related to the recognition of excess tax benefits and deficiencies as income tax expense or benefit on a modified retrospective basis. In addition, the Company elected to report cash flows related to excess tax benefits on a prospective basis. The presentation requirements for cash flows related to employee taxes paid for withheld shares had no impact to the Company’s statement of cash flows since such cash flows have historically been presented as a financing activity. In July 2015, the FASB issued an accounting standards update which simplifies the measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. The new standard applies only to inventories for which cost is determined by methods other than last-in-first-out and the retail inventory method. Effective in the first quarter of fiscal 2017, the Company adopted this guidance. The adoption of this guidance did not have a significant impact on the Company’s consolidated financial condition and results of operation. Accounting Standards Not Yet Adopted In January 2017, the Financial Accounting Standards Board (the "FASB") issued an accounting standard update which simplifies the subsequent measurement of goodwill and removes step 2 from the goodwill impairment test. Instead, an entity should record an impairment charge based on excess of a reporting unit’s carrying amount over its fair value. The standard is effective for public companies for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated financial condition and results of operations. In October 2016, the FASB issued an accounting standard update which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. This standard will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting period within those annual periods. Early adoption is permitted. This standard update is required to be adopted using the modified retrospective approach, with a cumulative catch-up adjustment to retained earnings in the period of adoption. The Company is currently evaluating the impact of adopting this standard on its consolidated financial condition and results of operations. In August 2016, the FASB issued an accounting standard which addresses eight specific cash flow classification issues. This update is effective for public companies for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption is permitted, including in an interim period. If early adopted in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period, and all the amendments must be adopted in the same period. The standard is to be applied through a retrospective transition method to each period presented. If it is impracticable to apply retrospectively for some of the issues, the amendments for those issues would be applied prospectively as of the earliest date practicable. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated statement of cash flows. In June 2016, the FASB issued an accounting standard which requires measurement and timely recognition of expected credit losses for financial assets. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The standard is to be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is currently evaluating the effect of this update on its consolidated financial condition and results of operations. In February 2016, the FASB issued an accounting standards update which requires lessees to record a right-of-use asset and a corresponding lease liability on the balance sheet (with the exception of short-term leases). For lessees, leases will continue to be classified as either operating or financing in the income statement. The standard is effective for public companies for annual reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. This standard is required to be applied with a modified retrospective transition approach. The Company generally does not finance purchases of equipment or other capital, but does lease some equipment and facilities. The Company is currently evaluating the impact of this standard on its consolidated financial statements and related disclosures but anticipates most its existing operating lease commitments will be recognized as operating lease liabilities and right-of-use assets. In May 2014, the FASB issued an accounting standards update which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method. In August 2015, the FASB deferred for one year the effective date of the new revenue standard, with early adoption permitted but not earlier than the original effective date. Consequently, the new standard will be effective for the Company on December 31, 2017 and the Company does not plan to adopt early. Based on the Company’s current assessment, the Company expects to adopt the new guidance in the first quarter of fiscal 2018 by using the modified retrospective method of transition. While the Company continues to assess the impact of the new standard, the Company believes that the timing of revenue recognition for certain systems and performance obligations, will generally occur earlier than under current revenue recognition guidance. Under current U.S. GAAP, revenue for certain systems or performance obligations is delayed until formal customer sign-off has occurred and/or contractual obligations have been met, whereas under the new standard, revenue should be recorded when transfer of control has occurred, which is normally upon shipment. While the Company currently expects revenue related to these arrangements to remain unchanged in total, the nature of when control transfers may change the timing of revenue recognition. Additionally, the Company believes the adoption of the new standard will most likely not result in a different set of performance obligations, when compared to current GAAP. The Company further believes that required changes to its current business processes and IT systems, to comply with the new standard, will be minor in nature. Other aspects of the standard, including the capitalization of costs related to the acquisition and/or fulfillment of the Company’s contracts are still being evaluated, but the Company believes impacts will be either minor or immaterial. The Company is currently evaluating the impact of the new standard on the Company’s contracts with customers and will continue to monitor industry activities and other guidance provided by the accounting profession and regulators and adjust its approach and implementation plans as required.

Fair Value Measurements and Dis

Fair Value Measurements and Disclosures	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements and Disclosures	Note 3. Fair Value Measurements and Disclosures The Company determines the fair values of its financial instruments based on the fair value hierarchy established in FASB Accounting Standards Codification (“ASC”) 820, Fair Value Measurement Level 1 — Quoted prices in active markets for identical assets or liabilities. Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3 — Unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Such unobservable inputs include an estimated discount rate used in the Company’s discounted present value analysis of future cash flows, which reflects the Company’s estimate of debt with similar terms in the current credit markets. As there is currently minimal activity in such markets, the actual rate could be materially different. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The standard assumes that the transaction to sell the asset or transfer the liability occurs in the principal or most advantageous market for the asset or liability and establishes that the fair value of an asset or liability shall be determined based on the assumptions that market participants would use in pricing the asset or liability. The following tables present the Company’s assets and liabilities measured at estimated fair value on a recurring basis, excluding accrued interest components, categorized in accordance with the fair value hierarchy (in thousands), as of the following dates: September 30, 2017 December 31, 2016 Fair Value Measurements Using Input Types Fair Value Measurements Using Input Types Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 812 $ — $ — $ 812 $ 959 $ — $ — $ 959 Commercial paper and corporate debt securities — 4,994 — 4,994 — 2,499 — 2,499 Total cash equivalents $ 812 $ 4,994 $ — $ 5,806 $ 959 $ 2,499 $ — $ 3,458 Marketable securities: U.S. Treasury securities and U.S. Government agency debt securities — 2,497 — 2,497 — 17,072 — 17,072 Certificates of deposits — 23,298 — 23,298 — 23,019 — 23,019 Commercial paper — 17,910 — 17,910 — 22,402 — 22,402 Municipal securities and corporate debt securities — 45,697 — 45,697 — 14,943 — 14,943 Asset-backed Securities — 6,914 — 6,914 — 5,463 — 5,463 Total marketable securities $ — $ 96,316 $ — $ 96,316 $ - $ 82,899 $ — $ 82,899 Total (1) $ 812 $ 101,310 $ — $ 102,122 $ 959 $ 85,398 $ — $ 86,357 (1) See “Note 4. Cash and Investments” of the Notes to Consolidated Financial Statements for more information. The fair values of the marketable securities that are classified as Level 1 in the table above were derived from quoted market prices for identical assets or liabilities in active markets that the Company has the ability to access. The fair value of marketable securities that are classified as Level 2 in the table above were derived from non-binding market consensus prices that were corroborated by observable market data, quoted market prices for similar instruments, or pricing models, such as discounted cash flow techniques with all significant inputs derived from or corroborated by observable market data. There were no transfers of instruments between Level 1, Level 2 and Level 3 during the financial periods presented. Derivatives The Company uses foreign currency exchange forward contracts to mitigate variability in gains and losses generated from the re-measurement of certain monetary assets and liabilities denominated in foreign currencies. These derivatives are carried at fair value with changes recorded in other income (expense), net in the consolidated statements of operations. Changes in the fair value of these derivatives are largely offset by re-measurement of the underlying assets and liabilities. The derivatives have maturities of approximately 30 days. The settlement of forward foreign currency contracts included in the three months ended September 30, 2017 and September 24, 2016 was a gain of $0.3 million and $0.1 million, respectively. The settlement of forward foreign currency contracts included in the nine months ended September 30, 2017 and September 24, 2016 was a gain of $1.0 million and a loss of $1.2 million, respectively. These are included in other income (expense), net, in the consolidated statements of operations. The following table presents the notional amounts and fair values of the Company’s outstanding derivative instruments in U.S. Dollar equivalent (in millions): As of September 30, 2017 As of December 31, 2016 Fair Value Fair Value Notional Amount Asset Liability Notional Amount Asset Liability Undesignated Hedges: Forward Foreign Currency Contracts Purchase $ 21.6 — $ 0.1 $ 12.6 — — Sell $ 16.6 — $ 0.1 $ 1.3 — —

Cash and Investments

Cash and Investments	9 Months Ended
	Sep. 30, 2017
Investments Debt And Equity Securities [Abstract]
Cash and Investments	Note 4. Cash and Investments The following tables present cash, cash equivalents, and available-for-sale investments as of the following dates (in thousands): September 30, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 38,235 $ — $ — $ 38,235 Cash equivalents: Money market funds 812 — — 812 Commercial paper and corporate debt securities 4,994 — — 4,994 Marketable securities: U.S. Treasury securities 501 — — 501 U.S. Government agency securities 2,001 — (5 ) 1,996 Certificate of deposits 23,298 — — 23,298 Commercial paper 17,907 3 — 17,910 Corporate debt securities 45,701 — (4 ) 45,697 Asset-backed securities 6,916 — (2 ) 6,914 Total cash, cash equivalents, and marketable securities $ 140,365 $ 3 $ (11 ) $ 140,357 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 43,604 $ — $ — $ 43,604 Cash equivalents: Money market funds 959 — — 959 Commercial paper and corporate debt securities 2,499 — — 2,499 Marketable securities: U.S. Treasury securities 5,667 — — 5,667 U.S. Government agency securities 11,412 — (7 ) 11,405 Certificates of deposits 23,000 19 — 23,019 Commercial paper 22,402 — — 22,402 Corporate debt securities 14,194 — (6 ) 14,188 Municipal securities 756 — (1 ) 755 Asset-backed securities 5,466 — (3 ) 5,463 Total cash, cash equivalents, and marketable securities $ 129,959 $ 19 $ (17 ) $ 129,961 Available-for-sale marketable securities, readily convertible to cash, with maturity dates of 90 days or less are classified as cash equivalents, while those with maturity dates greater than 90 days are classified as marketable securities within short-term assets. All marketable securities as of September 30, 2017 and December 31, 2016, were available-for-sale and reported at fair value based on the estimated or quoted market prices as of the balance sheet date. Realized gains and losses on sale of securities are recorded in other income (expense), net, in the Company’s statement of operations. For the three months ended September 30, 2017 and September 24, 2016, net realized gains and losses were not material. For the nine months ended September 30, 2017 and September 24, 2016, net realized gains and losses were $0.9 million and $0.3 million, respectively. Unrealized gains or losses, net of tax effect, are recorded in accumulated other comprehensive income (loss) within stockholders’ equity. Both the gross unrealized gains and gross unrealized losses for the three and nine months ended September 30, 2017 and September 24, 2016 were not material and no marketable securities had other than temporary impairment. All marketable securities as of September 30, 2017 and December 31, 2016, had maturity dates of less than two years.

Accounts Receivable

Accounts Receivable	9 Months Ended
	Sep. 30, 2017
Receivables [Abstract]
Accounts Receivable	Note 5. Accounts Receivable The Company maintains arrangements under which eligible accounts receivable in Japan are sold without recourse to unrelated third-party financial institutions. These receivables were not included in the consolidated balance sheets as the criteria for sale treatment had been met. The Company pays administrative fees as well as interest ranging from 0.61% to 1.68% based on the anticipated length of time between the date the sale is consummated and the expected collection date of the receivables sold. The Company sold $6.1 million and $10.1 million of receivables during the three months ended September 30, 2017 and September 24, 2016, respectively, and $15.5 and $29.6 million of receivables during the nine months ended September 30, 2017 and September 24, 2016. There were no material gains or losses on the sale of such receivables. There were no amounts due from such third party financial institutions at September 30, 2017 and December 31, 2016.

Financial Statement Components

Financial Statement Components	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Financial Statement Components	Note 6. Financial Statement Components The following tables provide details of selected financial statement components as of the following dates (in thousands): At September 30, 2017 December 31, 2016 Inventories: Raw materials and sub-assemblies $ 31,772 $ 23,506 Work in process 18,280 10,347 Finished goods 4,968 4,984 Inventories 55,020 38,837 Inventories-delivered systems 3,320 2,457 Total inventories $ 58,340 $ 41,294 Property, plant and equipment, net: (1) Land $ 15,571 $ 15,568 Building and improvements 20,649 20,532 Machinery and equipment 35,428 35,659 Furniture and fixtures 2,289 2,282 Software 9,261 9,756 Capital in progress 1,825 2,748 Total property, plant and equipment, gross 85,023 86,545 Accumulated depreciation and amortization (42,706 ) (42,319 ) Total property, plant and equipment, net $ 42,317 $ 44,226 (1) Other Current Liabilities: Accrued warranty $ 4,542 $ 3,838 Customer deposits 67 581 Retrofit liability 353 432 Accrued professional services 784 424 Accrued royalties 60 1,233 Other 1,898 1,539 Total other current liabilities $ 7,704 $ 8,047 Components of Accumulated Other Comprehensive Income (Loss) Foreign Currency Translations Defined Benefit Pension Plans Unrealized Income (Loss) on Investment Accumulated Other Comprehensive Income Balance as of December 31, 2016 $ (5,817 ) $ (227 ) $ (2 ) $ (6,046 ) Current period change 3,470 — (2 ) 3,468 Balance as of September 30, 2017 $ (2,347 ) $ (227 ) $ (4 ) $ (2,578 ) The items above, except for unrealized income (loss) on investment, did not impact the Company’s income tax provision. The amounts reclassified from each component of accumulated other comprehensive income (loss) into income statement line items were insignificant.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Note 7. Goodwill and Intangible Assets The following table summarizes the activity in the Company’s goodwill during the nine months ended September 30, 2017: (in thousands) Balance as of December 31, 2016 $ 8,940 Foreign currency movements 1,159 Balance as of September 30, 2017 $ 10,099 Finite-lived intangible assets are recorded at cost, less accumulated amortization. Finite-lived intangible assets as of September 30, 2017 and December 31, 2016 consisted of the following (in thousands): September 30, 2017 Adjusted cost Accumulated amortization Net carrying amount Developed technology $ 18,758 $ (16,517 ) $ 2,241 Customer relationships 9,426 (9,426 ) — Brand names 1,927 (1,927 ) — Patented technology 2,252 (2,235 ) 17 Trademark 80 (80 ) — Total $ 32,443 $ (30,185 ) $ 2,258 December 31, 2016 Adjusted cost Accumulated amortization Net carrying amount Developed technology $ 15,726 $ (15,380 ) $ 346 Customer relationships 9,322 (9,322 ) — Brand names 1,927 (1,927 ) — Patented technology 2,252 (2,186 ) 66 Trademark 80 (80 ) — Total $ 29,307 $ (28,895 ) $ 412 The amortization of finite-lived intangibles is computed using the straight-line method. Estimated lives of finite-lived intangibles range from two to ten years. The total amortization expense for the three months ended September 30, 2017 and September 24, 2016 was $0.1 million and $0.4 million, respectively. Total amortization expense for the nine months ended September 30, 2017 and September 24, 2016 was $0.2 million and $1.3 million, respectively. There were no impairment charges related to intangible assets recorded during the three and nine months ended September 30, 2017 and September 24, 2016. The estimated future amortization expense of finite intangible assets as of September 30, 2017 is as follows (in thousands): Fiscal Years Amounts 2017 (remaining three months) 52 2018 283 2019 352 2020 286 Thereafter 1,285 Total future amortization expense $ 2,258

Warranties

Warranties	9 Months Ended
	Sep. 30, 2017
Product Warranties Disclosures [Abstract]
Warranties	Note 8. Warranties The Company generally sells its products with a 12 months repair or replacement warranty from the date of acceptance or shipment date. The Company provides an accrual for estimated future warranty costs based upon the historical relationship of warranty costs to the cost of products sold. The estimated future warranty obligations related to product sales are recorded in the period in which the related revenue is recognized. The estimated future warranty obligations are affected by the warranty periods, sales volumes, product failure rates, material usage, and labor and replacement costs incurred in correcting a product failure. If actual product failure rates, material usage, labor or replacement costs were to differ from the Company’s estimates, revisions to the estimated warranty obligations would be required. For new product introductions where limited or no historical information exists, the Company may use warranty information from other previous product introductions to guide it in estimating its warranty accrual. Components of the warranty accrual, which were included in the accompanying condensed consolidated balance sheets with other current liabilities, were as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Balance as of beginning of period $ 4,602 $ 4,556 $ 3,838 $ 4,504 Accruals for warranties issued during period 1,020 1,100 3,800 3,529 Settlements during the period (1,080 ) (1,471 ) (3,096 ) (3,848 ) Balance as of end of period $ 4,542 $ 4,185 $ 4,542 $ 4,185

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 9. Commitments and Contingencies Intellectual Property Indemnification Obligations – The Company will, from time to time, in the normal course of business, agree to indemnify certain customers, vendors or others against third party claims that the Company’s products, when used for their intended purpose(s), or the Company’s intellectual property, infringe the intellectual property rights of such third parties or other claims made against parties with whom it enters into contractual relationships. It is not possible to determine the maximum potential amount of liability under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances that are likely to be involved in each particular claim. Historically, the Company has not made payments under these obligations and believes that the estimated fair value of these agreements is immaterial. Accordingly, no liabilities have been recorded for these obligations in the accompanying condensed consolidated balance sheets as of September 30, 2017 and December 31, 2016. Legal Proceedings - From time to time, the Company is subject to various legal proceedings or claims arising in the ordinary course of business. On August 2, 2017, the Company was named as defendant in a complaint filed in New Hampshire Superior Court (“Complaint”). The Complaint, brought by Optical Solutions, Inc. (“OSI”), alleges claims arising from a purported exclusive purchase contract between OSI and the Company pertaining to certain product. On September 18, 2017, the Company removed the action to the United States District Court for the District of New Hampshire. On September 25, 2017, the Company moved to transfer the Complaint to the Northern District of California and to dismiss all claims in the Complaint for lack of personal jurisdiction and for failure to state a claim. On September 27, 2017, OSI filed a motion to remand. OSI has not yet responded to the Company’s motions to transfer or dismiss. The Company records a provision for a loss when it believes that it is both probable that a loss has been incurred and the amount can be reasonably estimated. Based on current information, the Company believes it does not have any probable and reasonably estimable losses related to any current legal proceedings and claims. Although it is difficult to predict the outcome of legal proceedings, the Company believes that any liability that may ultimately arise from the resolution of these ordinary course matters will not have a material adverse effect on the business, financial condition and results of operations.

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Net Income Per Share	Note 10. Net Income Per Share The Company presents both basic and diluted net income per share on the face of its condensed consolidated statements of operations. Basic net income per share excludes the effect of potentially dilutive shares and is computed by dividing net income by the weighted-average number of shares of common stock outstanding for the period. Diluted net income per share is computed using the weighted-average number of shares of common stock outstanding for the period plus the effect of all dilutive securities representing potential shares of common stock outstanding during the period. A reconciliation of the share denominator of the basic and diluted net income per share computations for three and nine months ended September 30, 2017 and September 24, 2016 is as follows (in thousands): Three Month Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Weighted average common shares outstanding used in basic net income (loss) per share calculation 25,494 24,826 25,320 24,550 Potential dilutive common stock equivalents, using treasury stock method 438 456 613 429 Weighted average shares used in diluted net income (loss) per share calculation 25,932 25,282 25,933 24,979

Stockholders' Equity and Stock-

Stockholders' Equity and Stock-Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stockholders' Equity and Stock-Based Compensation	Note 11. Stockholders’ Equity and Stock-Based Compensation Options and Employee Stock Purchase Plan (“ESPP”) Awards The fair value of each option and ESPP award is estimated on the grant date using the Black-Scholes valuation model and the assumptions noted in the following table. The expected lives of options granted were calculated using the simplified method allowed by the Staff Accounting Bulletin No. 107, Share-Based Payment Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Employee Stock Purchase Plan: Expected life 0.5 years 0.5 years 0.5 years 0.5 years Volatility 38.9% 38.2% 37.2 % 38.7% Risk free interest rate 1.13% 0.37% 0.91 % 0.44% Dividends — — — — No stock options were awarded during the nine months ended September 30, 2017 and September 24, 2016, respectively. A summary of activity of stock options during the nine months ended September 30, 2017 is as follows: Number of Shares Outstanding (Options) Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in Options Outstanding at December 31, 2016 440,545 $ 15.06 2.12 $ 4,405 Exercised (180,629 ) $ 13.58 Cancelled (855 ) $ 16.63 Outstanding at September 30, 2017 259,061 $ 16.09 1.81 $ 3,293 Exercisable at September 30, 2017 255,665 $ 16.06 1.79 $ 3,256 The aggregate intrinsic value in the above table represents the total pretax intrinsic value, based on the Company’s closing stock price of $28.80 as of September 29, 2017, the last trading day of the quarter, which would have been received by the option holders had all option holders exercised their options as of that date. The total intrinsic value of options exercised during the three months ended September 30, 2017 and September 24, 2016 was $1.0 million and $0.5 million, respectively, and during the nine months ended September 30, 2017 and September 24, 2016 was $2.4 and $1.9 million, respectively. Restricted Stock Units (“RSUs”) Time-based RSUs are valued using the market value of the Company’s common stock on the date of grant, assuming no expectation of dividends paid. A summary of activity for RSUs is as follows: Summary of activity for RSUs Number of RSUs Weighted Average Fair Value Outstanding RSUs as of December 31, 2016 819,785 $ 16.79 Granted 340,070 $ 27.29 Released (356,619 ) $ 16.79 Cancelled (44,046 ) $ 17.21 Outstanding RSUs as of September 30, 2017 759,190 $ 21.48 Market-Based Performance Stock Units (“PSUs”) In addition to granting RSUs that vest on the passage of time only, the Company granted PSUs to key executives. The PSUs vest in three equal tranches over one, two and three years based on the relative performance of the Company’s stock during those periods, compared to a peer group over the same period. If target stock price performance is achieved, 66.7% of the shares of the Company’s common stock subject to the PSUs will vest. Up to a maximum of 100% of the shares subject to the PSUs will vest if the maximum stock price performance is achieved for each tranche. A summary of activity for PSUs is as follows: Summary of activity for PSUs Number of PSUs Weighted Average Fair Value Outstanding PSUs as of December 31, 2016 107,500 $ 9.94 Granted 59,550 26.75 Released (38,500 ) 10.41 Cancelled (4,000 ) 12.64 Outstanding PSUs as of September 30, 2017 124,550 $ 17.86 The preceding table reflects the maximum awards that can be achieved upon full vesting. Valuation of PSUs On the date of grant, the Company estimated the fair value of PSUs using a Monte Carlo simulation model. The assumptions for the valuation of PSUs are summarized as follows: 2017 Award 2016 Award Grant Date Fair Value Per Share 26.75 $ 8.52 Weighted-average assumptions/inputs: Expected Dividend — — Range of risk-free interest rates 1.40% 0.92% Range of expected volatilities for peer group 23%-62% 22%-93% Stock-based Compensation Expense Stock-based compensation expense for all share-based payment awards made to the Company’s employees and directors pursuant to the employee stock option and employee stock purchase plans by function were as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Cost of products $ 216 $ 116 $ 628 $ 273 Cost of service 161 138 463 355 Research and development 509 387 1,262 985 Selling 639 537 1,707 1,492 General and administrative 922 822 2,715 2,327 Total stock-based compensation expense related to employee stock options and employee stock purchases $ 2,447 $ 2,000 $ 6,775 $ 5,432

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Note 12. Income Taxes The Company accounts for income taxes under the provisions of ASC 740, Accounting for Income Taxes. The Company adjusts its effective tax rate each quarter to be consistent with the estimated annual effective tax rate. The Company also records the tax effect of unusual or infrequently occurring discrete items, including changes in judgment about valuation allowances and effects of changes in tax laws or tax rates, in the interim period in which they occur. The Company's effective tax rate reflects the impact of a portion of its earnings being taxed in foreign jurisdictions as well as a valuation allowance maintained on certain deferred tax assets. The provision for income taxes consists of the following (in thousands): Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Provision for income taxes $ 1,756 $ 1,332 $ 4,492 $ 2,568 The Company recorded a tax provision of $1.8 million and $1.3 million for the three months ended September 30, 2017 and September 24, 2016, respectively. The increase in the tax provision for 2017 from 2016 was primarily related to the additional utilization of U.S. deferred tax assets for the three months ending September 24, 2016 as the Company, at that time, was recording a valuation allowance against its U.S. deferred tax assets. The Company recorded a tax provision of $4.5 million and $2.6 million for the nine months ended September 30, 2017 and September 24, 2016, respectively. The increase in the tax provision for 2017 from 2016 was primarily related to the additional utilization of U.S. deferred tax assets for the nine months ending September 24, 2016 as the Company, at that time, was recording a valuation allowance against its U.S. deferred tax assets. The increase in the tax provision is also due to an increase in Company’s profitability for the nine months ended September 30, 2017. The Company continues to maintain a valuation allowance against its California and certain foreign deferred tax assets as a result of uncertainties regarding the realization of the assets due to cumulative losses and uncertainty of future taxable income. The Company will continue to assess the realizability of the deferred tax assets in each of the applicable jurisdictions and maintain the valuation allowances until sufficient positive evidence exists to support a reversal. In the event the Company determines that the deferred tax assets are realizable, an adjustment to the valuation allowance will be reflected in the tax provision for the period such determination is made. The Company is subject to taxation in the U.S. and various states including California, and foreign jurisdictions including Korea, Japan, Taiwan, China, Singapore, Germany, U.K., France, and Israel. Due to tax attribute carry-forwards, the Company is subject to examination for tax years 2003 forward for U.S. tax purposes. The Company is also subject to examination in various states for tax years 2002 forward. The Company is subject to examination for tax years 2007 forward for various foreign jurisdictions. The Company accrues interest and penalties related to unrecognized tax benefits in its provision for income taxes. The total amount of penalties and interest were not material as of September 30, 2017 and September 24, 2016. During the next twelve months, the Company anticipates increases in its unrecognized tax benefits of approximately $0.4 million.

Segment, Geographic, Product an

Segment, Geographic, Product and Significant Customer Information	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment, Geographic, Product and Significant Customer Information	Note 13. Segment, Geographic, Product and Significant Customer Information The Company has one operating segment, which is the sale, design, manufacture, marketing and support of optical critical dimension and thin film systems. The following tables summarize total net revenues and long-lived assets (excluding intangible assets) attributed to significant countries (in thousands): Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Total net revenues (1): South Korea $ 22,269 $ 15,710 $ 72,388 $ 35,226 Japan 4,781 11,765 17,400 24,669 United States 6,231 8,211 28,101 24,306 China 3,403 7,364 17,420 33,883 Taiwan 2,304 6,334 19,016 16,962 Singapore 9,774 5,078 12,229 18,645 Other 7,913 4,252 13,862 8,279 Total net revenues $ 56,675 $ 58,714 $ 180,416 $ 161,970 September 30, 2017 December 31, 2016 Long-lived tangible assets: United States $ 41,002 $ 42,688 International 1,315 1,538 Total long-lived tangible assets $ 42,317 $ 44,226 The following customers accounted for 10% or more of total accounts receivable, net: At September 30, 2017 December 31, 2016 Samsung Electronics Co. Ltd. 23% 14% Micron Technology, Inc. 27% 12% Taiwan Semiconductor Manufacturing Company Limited *** 20% Intel Corporation 11% 11% Toshiba Corporation *** 10% *** The customer accounted for less than 10% of total accounts receivable, net, as of that period end. The following customers accounted for 10% or more of total net revenues: Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Samsung Electronics Co. Ltd. 32% *** 28% *** SK Hynix *** 19% 15% 14% Intel Corporation 14% 19% 12% 19% Micron Technology, Inc. 19% 15% 11% 25% *** The customer accounted for less than 10% of total net revenues during the period.

Nature of Business and Basis 20

Nature of Business and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	Description of Business – Nanometrics Incorporated (“Nanometrics” or the “Company”) and its wholly-owned subsidiaries design, manufacture, market, sell and support optical critical dimension (“OCD”), thin film and overlay dimension metrology and inspection systems used primarily in the manufacturing of semiconductors, solar photovoltaics (“solar PV”) and high-brightness LEDs (“HB-LED”), as well as by customers in the silicon wafer and data storage industries. Nanometrics’ metrology systems precisely measure a wide range of film types deposited on substrates during manufacturing to control manufacturing processes and increase production yields in the fabrication of integrated circuits. The Company’s OCD technology is a patented critical dimension measurement technology that is used to precisely determine the dimensions on the semiconductor wafer that directly control the resulting performance of the integrated circuit devices. The thin film metrology systems use a broad spectrum of wavelengths, high-sensitivity optics, proprietary software, and patented technology to measure the thickness and uniformity of films deposited on silicon and other substrates as well as their chemical composition. The overlay metrology systems are used to measure the overlay accuracy of successive layers of semiconductor patterns on wafers in the photolithography process. Nanometrics’ inspection systems are used to find defects on patterned and unpatterned wafers at nearly every stage of the semiconductor production flow. The corporate headquarters of Nanometrics is located in Milpitas, California.
Basis of Presentation	Basis of Presentation – The accompanying condensed consolidated financial statements (“financial statements”) have been prepared on a consistent basis with the audited consolidated financial statements as of December 31, 2016, and include all normal recurring adjustments necessary to fairly state the information set forth therein. All significant intercompany accounts and transactions have been eliminated in consolidation. The financial statements have been prepared in accordance with the regulations of the United States Securities and Exchange Commission (“SEC”) for interim periods in accordance with S-X Article 10, and, therefore, omit certain information and footnote disclosure necessary to present the statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The operating results for interim periods are not necessarily indicative of the operating results that may be expected for the entire year. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the fiscal year ended December 31, 2016, which were included in the Company’s Annual Report on Form 10-K filed with the SEC on March 3, 2017.
Fiscal Period	Fiscal Period – The Company uses a 52/53 week fiscal year ending on the last Saturday of the calendar year. All references to the quarter refer to Nanometrics’ fiscal quarter. The fiscal quarters reported herein are 13 week periods.
Use of Estimates	Use of Estimates – The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reported period. Actual results could differ materially from those estimates. Estimates are used for, but not limited to, revenue recognition, the provision for doubtful accounts, the provision for excess, obsolete, or slow-moving inventories, valuation of intangible and long-lived assets, warranty accruals, income taxes, valuation of stock-based compensation, and contingencies.
Revenue Recognition	Revenue Recognition – The Company derives revenue from the sale of process control metrology and inspection systems and related upgrades (“product revenue”) as well as spare part sales, billable service and service contracts (together “service revenue”). Upgrades are system software and hardware performance upgrades that extend the features and functionality of a product. Upgrades are included in product revenue, which consists of sales of complete, advanced process control metrology and inspection systems (the “system(s)”). Nanometrics’ systems consist of hardware and software components that function together to deliver the essential functionality of the system. Arrangements for sales of systems and upgrades often include defined customer-specified acceptance criteria. In summary, the Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the seller's price is fixed or determinable, and collectability is reasonably assured. For repeat product sales to existing customers, revenue recognition occurs at the time title and risk of loss transfer to the customer, which usually occurs upon shipment from the Company's manufacturing location, if it can be reliably demonstrated that the product has successfully met the defined customer specified acceptance criteria and all other recognition criteria have been met. For initial sales where the product has not previously met the defined customer specified acceptance criteria, product revenues are recognized upon the earlier of receipt of written customer acceptance or expiration of the contractual acceptance period. In Japan, where contractual terms with the customer specify risk of loss and title transfers upon customer acceptance, revenue is recognized upon receipt of written customer acceptance, provided that all other recognition criteria have been met. The Company warrants its products against defects in manufacturing. Upon recognition of product revenue, a liability is recorded for anticipated warranty costs. On occasion, customers request a warranty period longer than the Company's standard warranty. In those instances, where extended warranty services are separately quoted to the customer, the associated revenue is deferred and recognized as service revenue ratably over the term of the extended warranty period. The portion of service contracts and extended warranty services agreements that are uncompleted at the end of any reporting period are included in deferred revenue. The Company sells software that is considered to be an upgrade to a customer's existing systems. These standalone software upgrades are not essential to the tangible product's functionality and are accounted for under software revenue recognition rules which require vendor specific objective evidence (“VSOE”) of fair value to allocate revenue in a multiple element arrangement. Revenue from software sales is recognized when the software is delivered to the customer, provided that all other recognition criteria have been met. The majority of other upgrades are sold based on published specifications. For basic upgrades, revenue is recognized at the time title and risk of loss transfer to the customer which is usually upon shipment. For complex and extensive upgrades, specific acceptance or prior acceptance for a similar upgrade is required in order to recognize revenue. Revenue related to spare parts is recognized upon shipment. Revenue related to billable services is recognized as the services are performed. Service contracts may be purchased by the customer during or after the warranty period and revenue is recognized ratably over the service contract period. Frequently, the Company delivers products and various services in a single transaction. The Company's deliverables consist of tools, installation, upgrades, billable services, spare parts, and service contracts. The Company's typical multi-element arrangements include a sale of one or multiple tools that include installation and standard warranty. Other arrangements consist of a sale of tools bundled with service elements or delivery of different types of services. The Company's tools, upgrades, and spare parts are generally delivered to customers within a period of up to six months from order date. Installation is usually performed soon after delivery of the tool. The portion of revenue associated with installation is deferred based on relative selling price and that revenue is recognized upon completion of the installation and receipt of final acceptance. Billable services are billed on a time and materials basis and performed as requested by customers. Under service contract arrangements, services are provided as needed over the fixed arrangement term, which terms can be up to twelve months. The Company does not grant its customers a general right of return or any refund terms and imposes a penalty on orders cancelled prior to the scheduled shipment date. The Company evaluates its revenue arrangements to identify deliverables and to determine whether these deliverables are separable into multiple units of accounting. The Company allocates the arrangement consideration among the deliverables based on relative selling prices. The Company has established VSOE for some of its products and services when a substantial majority of selling prices falls within a narrow range when sold separately. For deliverables with no established VSOE, the Company uses best estimate of selling price to determine standalone selling price for such deliverable. The Company does not use third party evidence to determine standalone selling price since this information is not widely available in the market as the Company's products contain a significant element of proprietary technology and the solutions offered differ substantially from competitors. The Company has established a process for developing estimated selling prices, which incorporates historical selling prices, the effect of market conditions, gross margin objectives, pricing practices, as well as entity-specific factors. The Company monitors and evaluates estimated selling price on a regular basis to ensure that changes in circumstances are accounted for in a timely manner. When certain elements in multiple-element arrangements are not delivered, or accepted at the end of a reporting period, the relative selling prices of undelivered elements are deferred until these elements are delivered and/or accepted. If deliverables cannot be accounted for as separate units of accounting, the entire arrangement is accounted for as a single unit of accounting and revenue is deferred until all elements are delivered and all revenue recognition requirements are met.
Accounting Standards Adopted	Accounting Standards Adopted In March 2016, the FASB issued an accounting standards update that simplifies several aspects of the accounting for share-based payment award transactions, including income tax consequences, classification of awards as equity or liability, and classification on the statement of cash flows. The new standard requires adoption of certain amendments relevant to the Company to be applied using a modified retrospective transition method by means of cumulative effect adjustment to retained earnings as of the beginning of the fiscal year 2017. The new standard permits entities to make an accounting policy election related to how forfeitures will impact the recognition of compensation cost for stock-based compensation. The Company has elected to account for forfeitures as they occur and adopted this change on a modified retrospective basis. The cumulative effect of this change resulted in a $0.1 million increase to accumulated deficit as of January 1, 2017. Furthermore, the standard requires excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled rather than paid-in capital. The Company recorded the cumulative effect of this change as a $1.2 million reduction to accumulated deficit in the first quarter of fiscal 2017 to reflect the recognition of excess tax benefits in prior years, with a corresponding adjustment to deferred tax assets and long-term tax liabilities. The Company adopted the guidance related to the recognition of excess tax benefits and deficiencies as income tax expense or benefit on a modified retrospective basis. In addition, the Company elected to report cash flows related to excess tax benefits on a prospective basis. The presentation requirements for cash flows related to employee taxes paid for withheld shares had no impact to the Company’s statement of cash flows since such cash flows have historically been presented as a financing activity. In July 2015, the FASB issued an accounting standards update which simplifies the measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. The new standard applies only to inventories for which cost is determined by methods other than last-in-first-out and the retail inventory method. Effective in the first quarter of fiscal 2017, the Company adopted this guidance. The adoption of this guidance did not have a significant impact on the Company’s consolidated financial condition and results of operation.
Accounting Standards Not Yet Adopted	Accounting Standards Not Yet Adopted In January 2017, the Financial Accounting Standards Board (the "FASB") issued an accounting standard update which simplifies the subsequent measurement of goodwill and removes step 2 from the goodwill impairment test. Instead, an entity should record an impairment charge based on excess of a reporting unit’s carrying amount over its fair value. The standard is effective for public companies for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated financial condition and results of operations. In October 2016, the FASB issued an accounting standard update which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. This standard will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting period within those annual periods. Early adoption is permitted. This standard update is required to be adopted using the modified retrospective approach, with a cumulative catch-up adjustment to retained earnings in the period of adoption. The Company is currently evaluating the impact of adopting this standard on its consolidated financial condition and results of operations. In August 2016, the FASB issued an accounting standard which addresses eight specific cash flow classification issues. This update is effective for public companies for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption is permitted, including in an interim period. If early adopted in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period, and all the amendments must be adopted in the same period. The standard is to be applied through a retrospective transition method to each period presented. If it is impracticable to apply retrospectively for some of the issues, the amendments for those issues would be applied prospectively as of the earliest date practicable. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated statement of cash flows. In June 2016, the FASB issued an accounting standard which requires measurement and timely recognition of expected credit losses for financial assets. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The standard is to be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is currently evaluating the effect of this update on its consolidated financial condition and results of operations. In February 2016, the FASB issued an accounting standards update which requires lessees to record a right-of-use asset and a corresponding lease liability on the balance sheet (with the exception of short-term leases). For lessees, leases will continue to be classified as either operating or financing in the income statement. The standard is effective for public companies for annual reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. This standard is required to be applied with a modified retrospective transition approach. The Company generally does not finance purchases of equipment or other capital, but does lease some equipment and facilities. The Company is currently evaluating the impact of this standard on its consolidated financial statements and related disclosures but anticipates most its existing operating lease commitments will be recognized as operating lease liabilities and right-of-use assets. In May 2014, the FASB issued an accounting standards update which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method. In August 2015, the FASB deferred for one year the effective date of the new revenue standard, with early adoption permitted but not earlier than the original effective date. Consequently, the new standard will be effective for the Company on December 31, 2017 and the Company does not plan to adopt early. Based on the Company’s current assessment, the Company expects to adopt the new guidance in the first quarter of fiscal 2018 by using the modified retrospective method of transition. While the Company continues to assess the impact of the new standard, the Company believes that the timing of revenue recognition for certain systems and performance obligations, will generally occur earlier than under current revenue recognition guidance. Under current U.S. GAAP, revenue for certain systems or performance obligations is delayed until formal customer sign-off has occurred and/or contractual obligations have been met, whereas under the new standard, revenue should be recorded when transfer of control has occurred, which is normally upon shipment. While the Company currently expects revenue related to these arrangements to remain unchanged in total, the nature of when control transfers may change the timing of revenue recognition. Additionally, the Company believes the adoption of the new standard will most likely not result in a different set of performance obligations, when compared to current GAAP. The Company further believes that required changes to its current business processes and IT systems, to comply with the new standard, will be minor in nature. Other aspects of the standard, including the capitalization of costs related to the acquisition and/or fulfillment of the Company’s contracts are still being evaluated, but the Company believes impacts will be either minor or immaterial. The Company is currently evaluating the impact of the new standard on the Company’s contracts with customers and will continue to monitor industry activities and other guidance provided by the accounting profession and regulators and adjust its approach and implementation plans as required.

Fair Value Measurements and D21

Fair Value Measurements and Disclosures (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Assets and liabilities measurements at estimated fair value on recurring basis excluding accrued interest components	The following tables present the Company’s assets and liabilities measured at estimated fair value on a recurring basis, excluding accrued interest components, categorized in accordance with the fair value hierarchy (in thousands), as of the following dates: September 30, 2017 December 31, 2016 Fair Value Measurements Using Input Types Fair Value Measurements Using Input Types Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 812 $ — $ — $ 812 $ 959 $ — $ — $ 959 Commercial paper and corporate debt securities — 4,994 — 4,994 — 2,499 — 2,499 Total cash equivalents $ 812 $ 4,994 $ — $ 5,806 $ 959 $ 2,499 $ — $ 3,458 Marketable securities: U.S. Treasury securities and U.S. Government agency debt securities — 2,497 — 2,497 — 17,072 — 17,072 Certificates of deposits — 23,298 — 23,298 — 23,019 — 23,019 Commercial paper — 17,910 — 17,910 — 22,402 — 22,402 Municipal securities and corporate debt securities — 45,697 — 45,697 — 14,943 — 14,943 Asset-backed Securities — 6,914 — 6,914 — 5,463 — 5,463 Total marketable securities $ — $ 96,316 $ — $ 96,316 $ - $ 82,899 $ — $ 82,899 Total (1) $ 812 $ 101,310 $ — $ 102,122 $ 959 $ 85,398 $ — $ 86,357 (1) See “Note 4. Cash and Investments” of the Notes to Consolidated Financial Statements for more information.
Notional amounts and fair values of outstanding derivative instruments	The following table presents the notional amounts and fair values of the Company’s outstanding derivative instruments in U.S. Dollar equivalent (in millions): As of September 30, 2017 As of December 31, 2016 Fair Value Fair Value Notional Amount Asset Liability Notional Amount Asset Liability Undesignated Hedges: Forward Foreign Currency Contracts Purchase $ 21.6 — $ 0.1 $ 12.6 — — Sell $ 16.6 — $ 0.1 $ 1.3 — —

Cash and Investments (Tables)

Cash and Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Investments Debt And Equity Securities [Abstract]
Cash, Cash Equivalents and Available-for-Sale Investments	The following tables present cash, cash equivalents, and available-for-sale investments as of the following dates (in thousands): September 30, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 38,235 $ — $ — $ 38,235 Cash equivalents: Money market funds 812 — — 812 Commercial paper and corporate debt securities 4,994 — — 4,994 Marketable securities: U.S. Treasury securities 501 — — 501 U.S. Government agency securities 2,001 — (5 ) 1,996 Certificate of deposits 23,298 — — 23,298 Commercial paper 17,907 3 — 17,910 Corporate debt securities 45,701 — (4 ) 45,697 Asset-backed securities 6,916 — (2 ) 6,914 Total cash, cash equivalents, and marketable securities $ 140,365 $ 3 $ (11 ) $ 140,357 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 43,604 $ — $ — $ 43,604 Cash equivalents: Money market funds 959 — — 959 Commercial paper and corporate debt securities 2,499 — — 2,499 Marketable securities: U.S. Treasury securities 5,667 — — 5,667 U.S. Government agency securities 11,412 — (7 ) 11,405 Certificates of deposits 23,000 19 — 23,019 Commercial paper 22,402 — — 22,402 Corporate debt securities 14,194 — (6 ) 14,188 Municipal securities 756 — (1 ) 755 Asset-backed securities 5,466 — (3 ) 5,463 Total cash, cash equivalents, and marketable securities $ 129,959 $ 19 $ (17 ) $ 129,961

Financial Statement Components

Financial Statement Components (Tables)	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Selected financial statement components	The following tables provide details of selected financial statement components as of the following dates (in thousands): At September 30, 2017 December 31, 2016 Inventories: Raw materials and sub-assemblies $ 31,772 $ 23,506 Work in process 18,280 10,347 Finished goods 4,968 4,984 Inventories 55,020 38,837 Inventories-delivered systems 3,320 2,457 Total inventories $ 58,340 $ 41,294 Property, plant and equipment, net: (1) Land $ 15,571 $ 15,568 Building and improvements 20,649 20,532 Machinery and equipment 35,428 35,659 Furniture and fixtures 2,289 2,282 Software 9,261 9,756 Capital in progress 1,825 2,748 Total property, plant and equipment, gross 85,023 86,545 Accumulated depreciation and amortization (42,706 ) (42,319 ) Total property, plant and equipment, net $ 42,317 $ 44,226 (1) Other Current Liabilities: Accrued warranty $ 4,542 $ 3,838 Customer deposits 67 581 Retrofit liability 353 432 Accrued professional services 784 424 Accrued royalties 60 1,233 Other 1,898 1,539 Total other current liabilities $ 7,704 $ 8,047
Components of accumulated other comprehensive income (loss)	Components of Accumulated Other Comprehensive Income (Loss) Foreign Currency Translations Defined Benefit Pension Plans Unrealized Income (Loss) on Investment Accumulated Other Comprehensive Income Balance as of December 31, 2016 $ (5,817 ) $ (227 ) $ (2 ) $ (6,046 ) Current period change 3,470 — (2 ) 3,468 Balance as of September 30, 2017 $ (2,347 ) $ (227 ) $ (4 ) $ (2,578 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of goodwill	The following table summarizes the activity in the Company’s goodwill during the nine months ended September 30, 2017: (in thousands) Balance as of December 31, 2016 $ 8,940 Foreign currency movements 1,159 Balance as of September 30, 2017 $ 10,099
Summary of finite-lived intangible assets	Finite-lived intangible assets are recorded at cost, less accumulated amortization. Finite-lived intangible assets as of September 30, 2017 and December 31, 2016 consisted of the following (in thousands): September 30, 2017 Adjusted cost Accumulated amortization Net carrying amount Developed technology $ 18,758 $ (16,517 ) $ 2,241 Customer relationships 9,426 (9,426 ) — Brand names 1,927 (1,927 ) — Patented technology 2,252 (2,235 ) 17 Trademark 80 (80 ) — Total $ 32,443 $ (30,185 ) $ 2,258 December 31, 2016 Adjusted cost Accumulated amortization Net carrying amount Developed technology $ 15,726 $ (15,380 ) $ 346 Customer relationships 9,322 (9,322 ) — Brand names 1,927 (1,927 ) — Patented technology 2,252 (2,186 ) 66 Trademark 80 (80 ) — Total $ 29,307 $ (28,895 ) $ 412
Estimated future amortization expense	The estimated future amortization expense of finite intangible assets as of September 30, 2017 is as follows (in thousands): Fiscal Years Amounts 2017 (remaining three months) 52 2018 283 2019 352 2020 286 Thereafter 1,285 Total future amortization expense $ 2,258

Warranties (Tables)

Warranties (Tables)	9 Months Ended
	Sep. 30, 2017
Product Warranties Disclosures [Abstract]
Components of the warranty accrual	Components of the warranty accrual, which were included in the accompanying condensed consolidated balance sheets with other current liabilities, were as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Balance as of beginning of period $ 4,602 $ 4,556 $ 3,838 $ 4,504 Accruals for warranties issued during period 1,020 1,100 3,800 3,529 Settlements during the period (1,080 ) (1,471 ) (3,096 ) (3,848 ) Balance as of end of period $ 4,542 $ 4,185 $ 4,542 $ 4,185

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Reconciliation of the basic and diluted net income per share computations	A reconciliation of the share denominator of the basic and diluted net income per share computations for three and nine months ended September 30, 2017 and September 24, 2016 is as follows (in thousands): Three Month Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Weighted average common shares outstanding used in basic net income (loss) per share calculation 25,494 24,826 25,320 24,550 Potential dilutive common stock equivalents, using treasury stock method 438 456 613 429 Weighted average shares used in diluted net income (loss) per share calculation 25,932 25,282 25,933 24,979

Stockholders' Equity and Stoc27

Stockholders' Equity and Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee stock purchase plan assumptions	Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Employee Stock Purchase Plan: Expected life 0.5 years 0.5 years 0.5 years 0.5 years Volatility 38.9% 38.2% 37.2 % 38.7% Risk free interest rate 1.13% 0.37% 0.91 % 0.44% Dividends — — — —
Stock option plans activity	A summary of activity of stock options during the nine months ended September 30, 2017 is as follows: Number of Shares Outstanding (Options) Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in Options Outstanding at December 31, 2016 440,545 $ 15.06 2.12 $ 4,405 Exercised (180,629 ) $ 13.58 Cancelled (855 ) $ 16.63 Outstanding at September 30, 2017 259,061 $ 16.09 1.81 $ 3,293 Exercisable at September 30, 2017 255,665 $ 16.06 1.79 $ 3,256
Summary of activity for RSUs	A summary of activity for RSUs is as follows: Summary of activity for RSUs Number of RSUs Weighted Average Fair Value Outstanding RSUs as of December 31, 2016 819,785 $ 16.79 Granted 340,070 $ 27.29 Released (356,619 ) $ 16.79 Cancelled (44,046 ) $ 17.21 Outstanding RSUs as of September 30, 2017 759,190 $ 21.48
Summary of activity for PSUs	A summary of activity for PSUs is as follows: Summary of activity for PSUs Number of PSUs Weighted Average Fair Value Outstanding PSUs as of December 31, 2016 107,500 $ 9.94 Granted 59,550 26.75 Released (38,500 ) 10.41 Cancelled (4,000 ) 12.64 Outstanding PSUs as of September 30, 2017 124,550 $ 17.86
PSUs valuation assumptions	The assumptions for the valuation of PSUs are summarized as follows: 2017 Award 2016 Award Grant Date Fair Value Per Share 26.75 $ 8.52 Weighted-average assumptions/inputs: Expected Dividend — — Range of risk-free interest rates 1.40% 0.92% Range of expected volatilities for peer group 23%-62% 22%-93%
Stock-based compensation expense for all share-based payment awards	Stock-based compensation expense for all share-based payment awards made to the Company’s employees and directors pursuant to the employee stock option and employee stock purchase plans by function were as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Cost of products $ 216 $ 116 $ 628 $ 273 Cost of service 161 138 463 355 Research and development 509 387 1,262 985 Selling 639 537 1,707 1,492 General and administrative 922 822 2,715 2,327 Total stock-based compensation expense related to employee stock options and employee stock purchases $ 2,447 $ 2,000 $ 6,775 $ 5,432

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Provision for income taxes	The provision for income taxes consists of the following (in thousands): Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Provision for income taxes $ 1,756 $ 1,332 $ 4,492 $ 2,568

Segment, Geographic, Product 29

Segment, Geographic, Product and Significant Customer Information (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Total net revenue	The following tables summarize total net revenues and long-lived assets (excluding intangible assets) attributed to significant countries (in thousands) Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Total net revenues (1): South Korea $ 22,269 $ 15,710 $ 72,388 $ 35,226 Japan 4,781 11,765 17,400 24,669 United States 6,231 8,211 28,101 24,306 China 3,403 7,364 17,420 33,883 Taiwan 2,304 6,334 19,016 16,962 Singapore 9,774 5,078 12,229 18,645 Other 7,913 4,252 13,862 8,279 Total net revenues $ 56,675 $ 58,714 $ 180,416 $ 161,970
Long-lived tangible assets	September 30, 2017 December 31, 2016 Long-lived tangible assets: United States $ 41,002 $ 42,688 International 1,315 1,538 Total long-lived tangible assets $ 42,317 $ 44,226
Customers accounted for 10% or more of total accounts receivable	The following customers accounted for 10% or more of total accounts receivable, net: At September 30, 2017 December 31, 2016 Samsung Electronics Co. Ltd. 23% 14% Micron Technology, Inc. 27% 12% Taiwan Semiconductor Manufacturing Company Limited *** 20% Intel Corporation 11% 11% Toshiba Corporation *** 10% *** The customer accounted for less than 10% of total accounts receivable, net, as of that period end.
Customers accounted for 10% or more of total revenue	The following customers accounted for 10% or more of total net revenues: Three Months Ended Nine Months Ended September 30, 2017 September 24, 2016 September 30, 2017 September 24, 2016 Samsung Electronics Co. Ltd. 32% *** 28% *** SK Hynix *** 19% 15% 14% Intel Corporation 14% 19% 12% 19% Micron Technology, Inc. 19% 15% 11% 25% *** The customer accounted for less than 10% of total net revenues during the period.

Nature of Business and Basis 30

Nature of Business and Basis of Presentation - Textual (Details)	9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016
Accounting Policies [Line Items]
Fiscal year/fiscal quarter duration	91 days	91 days
Maximum period of delivery to customers	6 months
Maximum period services are provided over the fixed arrangement term	12 months
Minimum [Member]
Accounting Policies [Line Items]
Fiscal year/fiscal quarter duration	364 days
Maximum [Member]
Accounting Policies [Line Items]
Fiscal year/fiscal quarter duration	371 days

Recent Accounting Pronounceme31

Recent Accounting Pronouncements - Textual (Details) - USD ($) $ in Millions	Jan. 02, 2017	Apr. 01, 2017
Stock-based Compensation [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase (decrease) in accumulated deficit	$ 0.1	$ (1.2)

Fair Value Measurements and D32

Fair Value Measurements and Disclosures - Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Total marketable securities	$ 96,316	$ 82,899
Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	5,806	3,458
Total marketable securities	96,316	82,899
Total	102,122	86,357
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	812	959
Total marketable securities	0	0
Total	812	959
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	4,994	2,499
Total marketable securities	96,316	82,899
Total	101,310	85,398
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	0	0
Total marketable securities	0	0
Total	0	0
Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	812	959
Money market funds [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	812	959
Money market funds [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	0	0
Money market funds [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	0	0
Commercial paper and corporate debt securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	4,994	2,499
Commercial paper and corporate debt securities [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	0	0
Commercial paper and corporate debt securities [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	4,994	2,499
Commercial paper and corporate debt securities [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total cash equivalents	0	0
U.S. Treasury securities and U.S. Government agency debt securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	2,497	17,072
U.S. Treasury securities and U.S. Government agency debt securities [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
U.S. Treasury securities and U.S. Government agency debt securities [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	2,497	17,072
U.S. Treasury securities and U.S. Government agency debt securities [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Certificates of deposits [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	23,298	23,019
Certificates of deposits [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Certificates of deposits [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	23,298	23,019
Certificates of deposits [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Commercial paper [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	17,910	22,402
Commercial paper [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Commercial paper [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	17,910	22,402
Commercial paper [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Municipal securities and corporate debt securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	45,697	14,943
Municipal securities and corporate debt securities [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Municipal securities and corporate debt securities [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	45,697	14,943
Municipal securities and corporate debt securities [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	6,914	5,463
Asset-backed Securities [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	0	0
Asset-backed Securities [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	6,914	5,463
Asset-backed Securities [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total marketable securities	$ 0	$ 0

Fair Value Measurements and D33

Fair Value Measurements and Disclosures - Measured at Fair Value on Recurring Basis (Parenthetical) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	$ 5,806	$ 3,458
Cash [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	$ 38,200	$ 43,600

Fair Value Measurements and D34

Fair Value Measurements and Disclosures - Textual (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Fair Value Measurements and Disclosures (Textual) [Abstract]
Fair value assets among level 1, level 2 and level 3 transfers, amount	$ 0		$ 0
Forward Foreign Currency Contracts [Member]
Fair Value Measurements and Disclosures (Textual) [Abstract]
Derivative term			30 days
Forward Foreign Currency Contracts [Member] | Other Income (Expense), Net [Member]
Fair Value Measurements and Disclosures (Textual) [Abstract]
Gain (loss) on settlement of derivatives	$ 300,000	$ 100,000	$ 1,000,000	$ (1,200,000)

Fair Value Measurements and D35

Fair Value Measurements and Disclosures - Notional Amounts and Fair Values of Outstanding Derivative Instruments (Details) - Forward Foreign Currency Contracts [Member] - Not Designated as Hedging Instrument [Member] - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Purchase [Member]
Derivatives Fair Value [Line Items]
Notional Amount	$ 21,600,000	$ 12,600,000
Fair Value Asset	0	0
Fair Value Liability	100,000	0
Sell [Member]
Derivatives Fair Value [Line Items]
Notional Amount	16,600,000	1,300,000
Fair Value Asset	0	0
Fair Value Liability	$ 100,000	$ 0

Cash and Investments (Details)

Cash and Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 140,365	$ 129,959
Gross Unrealized Gains	3	19
Gross Unrealized Losses	(11)	(17)
Estimated Fair Market Value	140,357	129,961
U.S. Government agency securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,001	11,412
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5)	(7)
Estimated Fair Market Value	1,996	11,405
Commercial paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	17,907	22,402
Gross Unrealized Gains	3	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	17,910	22,402
Corporate debt securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	45,701	14,194
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(6)
Estimated Fair Market Value	45,697	14,188
Asset-backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	6,916	5,466
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	(3)
Estimated Fair Market Value	6,914	5,463
Cash [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	38,235	43,604
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	38,235	43,604
Money market funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	812	959
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	812	959
Certificates of deposits [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	23,298	23,000
Gross Unrealized Gains	0	19
Gross Unrealized Losses	0	0
Estimated Fair Market Value	23,298	23,019
U.S. Treasury securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	501	5,667
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	501	5,667
Commercial paper and corporate debt securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	4,994	2,499
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	$ 4,994	2,499
Municipal securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		756
Gross Unrealized Gains		0
Gross Unrealized Losses		(1)
Estimated Fair Market Value		$ 755

Cash and Investments - Addition

Cash and Investments - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Net realized gains and losses on sale of securities	$ 0.9	$ 0.3
Investment maturity period, less than	2 years		2 years

Accounts Receivable - Textual (

Accounts Receivable - Textual (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016	Dec. 31, 2016
Accounts Receivable (Additional Textual) [Abstract]
Sold receivables amount	$ 6,100,000	$ 10,100,000	$ 15,500,000	$ 29,600,000
Due from unrelated third parties	$ 0		$ 0		$ 0
Minimum [Member]
Accounts Receivable (Textual) [Abstract]
Administrative fees as well as interest percent			0.61%
Maximum [Member]
Accounts Receivable (Textual) [Abstract]
Administrative fees as well as interest percent			1.68%

Financial Statement Component39

Financial Statement Components - Selected Financial Statement Components (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jul. 01, 2017	Dec. 31, 2016	Sep. 24, 2016	Jun. 25, 2016	Dec. 26, 2015
Inventories:
Raw materials and sub-assemblies	$ 31,772		$ 23,506
Work in process	18,280		10,347
Finished goods	4,968		4,984
Inventories	55,020		38,837
Inventories-delivered systems	3,320		2,457
Total inventories	58,340		41,294
Property, plant and equipment, net:
Total property, plant and equipment, gross	85,023		86,545
Accumulated depreciation and amortization	(42,706)		(42,319)
Total property, plant and equipment, net	42,317		44,226
Other Current Liabilities:
Accrued warranty	4,542	$ 4,602	3,838	$ 4,185	$ 4,556	$ 4,504
Customer deposits	67		581
Retrofit liability	353		432
Accrued professional services	784		424
Accrued royalties	60		1,233
Other	1,898		1,539
Total other current liabilities	7,704		8,047
Land [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	15,571		15,568
Building and improvements [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	20,649		20,532
Machinery and equipment [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	35,428		35,659
Furniture and fixtures [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	2,289		2,282
Software [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	9,261		9,756
Capital in progress [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	$ 1,825		$ 2,748

Financial Statement Component40

Financial Statement Components - Selected Financial Statement Components (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Depreciation and amortization expense	$ 1.6	$ 1.7	$ 5.1	$ 5.1

Financial Statement Component41

Financial Statement Components - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			$ 243,774
Current period change	$ 779	$ 520	3,468	$ 2,091
End of period	274,485		274,485
Foreign Currency Translations [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(5,817)
Current period change			3,470
End of period	(2,347)		(2,347)
Defined Benefit Pension Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(227)
End of period	(227)		(227)
Unrealized Income (Loss) on Investment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(2)
Current period change			(2)
End of period	(4)		(4)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(6,046)
End of period	$ (2,578)		$ (2,578)

Goodwill and Intangible Asset42

Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 8,940
Foreign currency movements	1,159
Ending balance	$ 10,099

Goodwill and Intangible Asset43

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Summary of Finite-lived intangible assets
Adjusted cost	$ 32,443	$ 29,307
Accumulated amortization	(30,185)	(28,895)
Finite lived intangible assets, Net carrying amount	2,258	412
Developed technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	18,758	15,726
Accumulated amortization	(16,517)	(15,380)
Finite lived intangible assets, Net carrying amount	2,241	346
Customer relationships [Member]
Summary of Finite-lived intangible assets
Adjusted cost	9,426	9,322
Accumulated amortization	(9,426)	(9,322)
Finite lived intangible assets, Net carrying amount	0	0
Brand names [Member]
Summary of Finite-lived intangible assets
Adjusted cost	1,927	1,927
Accumulated amortization	(1,927)	(1,927)
Finite lived intangible assets, Net carrying amount	0
Patented technology [Member]
Summary of Finite-lived intangible assets
Adjusted cost	2,252	2,252
Accumulated amortization	(2,235)	(2,186)
Finite lived intangible assets, Net carrying amount	17	66
Trademark [Member]
Summary of Finite-lived intangible assets
Adjusted cost	80	80
Accumulated amortization	(80)	(80)
Finite lived intangible assets, Net carrying amount	$ 0	$ 0

Goodwill and Intangible Asset44

Goodwill and Intangible Assets - Textual (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 100,000	$ 400,000	$ 200,000	$ 1,300,000
Impairment charges	$ 0	$ 0	$ 0	$ 0
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles estimated lives			2 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles estimated lives			10 years

Goodwill and Intangible Asset45

Goodwill and Intangible Assets - Future Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Estimated future amortization expense
2017 (remaining three months)	$ 52
2,018	283
2,019	352
2,020	286
Thereafter	1,285
Finite lived intangible assets, Net carrying amount	$ 2,258	$ 412

Warranties - Textual (Details)

Warranties - Textual (Details)	9 Months Ended
	Sep. 30, 2017
Product Warranties Disclosures [Abstract]
Product warranty period	12 months

Warranties (Details)

Warranties (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Components of the warranty accrual [Roll Forward]
Balance as of beginning of period	$ 4,602	$ 4,556	$ 3,838	$ 4,504
Accruals for warranties issued during period	1,020	1,100	3,800	3,529
Settlements during the period	(1,080)	(1,471)	(3,096)	(3,848)
Balance as of end of period	$ 4,542	$ 4,185	$ 4,542	$ 4,185

Commitments and Contingencies -

Commitments and Contingencies - Textual (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Liabilities recorded for obligations	$ 0	$ 0

Net Income Per Share (Details)

Net Income Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Reconciliation of the basic and diluted net income per share computations
Weighted average common shares outstanding used in basic net income (loss) per share calculation	25,494	24,826	25,320	24,550
Potential dilutive common stock equivalents, using treasury stock method	438	456	613	429
Weighted average shares used in diluted net income (loss) per share calculation	25,932	25,282	25,933	24,979

Stockholders' Equity and Stoc50

Stockholders' Equity and Stock-Based Compensation - Employee Stock Purchase Plan Assumptions (Details) - Employee Stock Purchase Plan [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Assumption of stock option's fair value
Expected life	6 months	6 months	6 months	6 months
Volatility	38.90%	38.20%	37.20%	38.70%
Risk free interest rate	1.13%	0.37%	0.91%	0.44%
Dividends	0.00%	0.00%	0.00%	0.00%

Stockholders' Equity and Stoc51

Stockholders' Equity and Stock-Based Compensation - Textual (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016	Sep. 29, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted			0	0
Closing stock price					$ 28.80
Intrinsic value of options exercised	$ 1	$ 0.5	$ 2.4	$ 1.9
Performance-Based Restricted Stock Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of granted shares that will vest if target stock price performance is achieved			66.70%
Maximum percent of granted shares that will vest if maximum stock price performance is achieved			100.00%
Performance-Based Restricted Stock Units (PSUs) [Member] | Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of vesting			1 year
Performance-Based Restricted Stock Units (PSUs) [Member] | Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of vesting			2 years
Performance-Based Restricted Stock Units (PSUs) [Member] | Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of vesting			3 years

Stockholders' Equity and Stoc52

Stockholders' Equity and Stock-Based Compensation - Summary of Activity of Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Activity of stock option plans [Roll Forward]
Number of Shares Outstanding (Options), Beginning Balance (in shares)	440,545
Number of Shares Outstanding (Options), Exercised (in shares)	(180,629)
Number of Shares Outstanding (Options), Cancelled (in shares)	(855)
Number of Shares Outstanding (Options), Ending Balance (in shares)	259,061	440,545
Number of Shares Outstanding (Options), Exercisable (in shares)	255,665
Weighted average exercise price for stock option plans [Roll Forward]
Weighted Average Exercise Price, Beginning Balance (in dollars per share)	$ 15.06
Weighted Average Exercise Price, Exercised (in dollars per share)	13.58
Weighted Average Exercise Price, Cancelled (in dollars per share)	16.63
Weighted Average Exercise Price, Ending Balance (in dollars per share)	16.09	$ 15.06
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 16.06
Weighted Average Remaining Contractual Term, Outstanding	1 year 9 months 22 days	2 years 1 month 13 days
Weighted Average Remaining Contractual Term, Exercisable	1 year 9 months 14 days
Aggregate Intrinsic Value, Outstanding	$ 3,293	$ 4,405
Aggregate Intrinsic Value, Exercisable	$ 3,256

Stockholders' Equity and Stoc53

Stockholders' Equity and Stock-Based Compensation - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) [Member]	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Activity for RSUs [Roll Forward]
Number of units Beginning balance (in shares) | shares	819,785
Number of units, Granted (in shares) | shares	340,070
Number of units, Released (in shares) | shares	(356,619)
Number of units, Cancelled (in shares) | shares	(44,046)
Number of units, Ending balance (in shares) | shares	759,190
Weighted Average Fair Value for RSUs [Roll Forward]
Weighted Average Fair Value, Beginning balance (in dollars per share) | $ / shares	$ 16.79
Weighted Average Fair Value, Granted (in dollars per share) | $ / shares	27.29
Weighted Average Fair Value, Released (in dollars per share) | $ / shares	16.79
Weighted Average Fair Value, Cancelled (in dollars per share) | $ / shares	17.21
Weighted Average Fair Value, Ending balance (in dollars per share) | $ / shares	$ 21.48

Stockholders' Equity and Stoc54

Stockholders' Equity and Stock-Based Compensation - Performance Stock Units Activity (Details) - Performance-Based Restricted Stock Units (PSUs) [Member] - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016
Activity for PSUs [Roll Forward]
Number of units Beginning balance (in shares)	107,500
Number of units, Granted (in shares)	59,550
Number of units, Released (in shares)	(38,500)
Number of units, Cancelled (in shares)	(4,000)
Number of units, Ending balance (in shares)	124,550
Weighted Average Fair Value for PSUs [Roll Forward]
Weighted Average Fair Value, Beginning balance (in dollars per share)	$ 9.94
Weighted Average Fair Value, Granted (in dollars per share)	26.75	$ 8.52
Weighted Average Fair Value, Released (in dollars per share)	10.41
Weighted Average Fair Value, Cancelled (in dollars per share)	12.64
Weighted Average Fair Value, Ending balance (in dollars per share)	$ 17.86

Stockholders' Equity and Stoc55

Stockholders' Equity and Stock-Based Compensation - Performance Stock Units Valuation Assumptions (Details) - Performance-Based Restricted Stock Units (PSUs) [Member] - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Fair Value Per Share (in dollars per share)	$ 26.75	$ 8.52
Expected Dividend	0.00%	0.00%
Risk free interest rate	1.40%	0.92%
Range of expected volatilities for peer group, minimum	23.00%	22.00%
Range of expected volatilities for peer group, maximum	62.00%	93.00%

Stockholders' Equity and Stoc56

Stockholders' Equity and Stock-Based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense related to employee stock options and employee stock purchases	$ 2,447	$ 2,000	$ 6,775	$ 5,432
Cost of products [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense related to employee stock options and employee stock purchases	216	116	628	273
Cost of service [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense related to employee stock options and employee stock purchases	161	138	463	355
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense related to employee stock options and employee stock purchases	509	387	1,262	985
Selling [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense related to employee stock options and employee stock purchases	639	537	1,707	1,492
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense related to employee stock options and employee stock purchases	$ 922	$ 822	$ 2,715	$ 2,327

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 1,756	$ 1,332	$ 4,492	$ 2,568

Income Taxes - Textual (Details

Income Taxes - Textual (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 1,756	$ 1,332	$ 4,492	$ 2,568
Anticipated increase in unrecognized tax benefits during next twelve months	$ 400		$ 400

Segment, Geographic, Product 59

Segment, Geographic, Product and Significant Customer Information - Textual (Details)	9 Months Ended
	Sep. 30, 2017segment
Segment Reporting [Abstract]
Number of operating segments	1

Segment, Geographic, Product 60

Segment, Geographic, Product and Significant Customer Information - Revenue Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Net revenues:
Total net revenues	$ 56,675	$ 58,714	$ 180,416	$ 161,970
South Korea [Member]
Net revenues:
Total net revenues	22,269	15,710	72,388	35,226
Japan [Member]
Net revenues:
Total net revenues	4,781	11,765	17,400	24,669
United States [Member]
Net revenues:
Total net revenues	6,231	8,211	28,101	24,306
China [Member]
Net revenues:
Total net revenues	3,403	7,364	17,420	33,883
Taiwan [Member]
Net revenues:
Total net revenues	2,304	6,334	19,016	16,962
Singapore [Member]
Net revenues:
Total net revenues	9,774	5,078	12,229	18,645
Other [Member]
Net revenues:
Total net revenues	$ 7,913	$ 4,252	$ 13,862	$ 8,279

Segment, Geographic, Product 61

Segment, Geographic, Product and Significant Customer Information - Long-lived Tangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Long-lived tangible assets:
Total long-lived tangible assets	$ 42,317	$ 44,226
United States [Member]
Long-lived tangible assets:
Total long-lived tangible assets	41,002	42,688
International [Member]
Long-lived tangible assets:
Total long-lived tangible assets	$ 1,315	$ 1,538

Segment, Geographic, Product 62

Segment, Geographic, Product and Significant Customer Information - Customers More Than 10% of Accounts Receivable (Details) - Accounts Receivable [Member] - Credit Concentration Risk [Member]	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Samsung Electronics Co. Ltd. [Member]
Customers accounted for 10% or more of total accounts receivable
Customers accounted for 10% or more of total accounts receivable	23.00%	14.00%
Micron Technology, Inc. [Member]
Customers accounted for 10% or more of total accounts receivable
Customers accounted for 10% or more of total accounts receivable	27.00%	12.00%
Taiwan Semiconductor Manufacturing Company Limited [Member]
Customers accounted for 10% or more of total accounts receivable
Customers accounted for 10% or more of total accounts receivable		20.00%
Intel Corporation [Member]
Customers accounted for 10% or more of total accounts receivable
Customers accounted for 10% or more of total accounts receivable	11.00%	11.00%
Toshiba Corporation [Member]
Customers accounted for 10% or more of total accounts receivable
Customers accounted for 10% or more of total accounts receivable		10.00%

Segment, Geographic, Product 63

Segment, Geographic, Product and Significant Customer Information - Customers More Than 10% of Revenues (Details) - Sales Revenue, Net [Member] - Customer Concentration Risk [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Samsung Electronics Co. Ltd. [Member]
Net revenues:
Customers accounted for 10% or more of total revenue	32.00%		28.00%
SK Hynix [Member]
Net revenues:
Customers accounted for 10% or more of total revenue		19.00%	15.00%	14.00%
Intel Corporation [Member]
Net revenues:
Customers accounted for 10% or more of total revenue	14.00%	19.00%	12.00%	19.00%
Micron Technology, Inc. [Member]
Net revenues:
Customers accounted for 10% or more of total revenue	19.00%	15.00%	11.00%	25.00%