Acacia Communications (ACIA) 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 27, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	Acacia Communications, Inc.
Trading Symbol	ACIA
Entity Central Index Key	1,651,235
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		39,377,330

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 115,761	$ 206,402
Marketable securities - short-term	173,388	104,004
Accounts receivable	95,622	108,127
Inventory	49,983	31,681
Prepaid expenses and other current assets	17,293	12,076
Deferred product costs	263	85
Total current assets	452,310	462,375
Marketable securities - long-term	59,315	0
Restricted cash	0	1,630
Property and equipment, net	25,090	25,124
Deferred tax asset	47,102	23,533
Other assets	8,984	4,274
Total assets	592,801	516,936
Current liabilities:
Accounts payable	38,180	49,430
Accrued liabilities	36,522	29,863
Deferred revenue	1,283	1,375
Total current liabilities	75,985	80,668
Other long-term liabilities	2,465	1,473
Total liabilities	78,450	82,141
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000 shares authorized; none issued and outstanding at September 30, 2017 and December 31, 2016	0	0
Common stock, $0.0001 par value; 150,000 shares authorized; 39,302 and 37,998 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively	4	4
Additional paid-in capital	316,595	295,893
Accumulated other comprehensive loss	(34)	(16)
Retained earnings	197,786	138,914
Total stockholders' equity	514,351	434,795
Total liabilities and stockholders' equity	$ 592,801	$ 516,936

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	39,302,000	37,998,000
Common stock, shares outstanding (in shares)	39,302,000	37,998,000

CONDENSED CONSOLIDATED INCOME S

CONDENSED CONSOLIDATED INCOME STATEMENTS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenue	$ 104,998	$ 135,304	$ 298,563	$ 335,985
Cost of revenue	58,856	72,004	170,739	183,327
Gross profit	46,142	63,300	127,824	152,658
Operating expenses:
Research and development	27,135	18,915	67,597	56,168
Sales, general and administrative	10,105	7,541	28,164	20,244
Gain on disposal of property and equipment	0	0	(47)	0
Total operating expenses	37,240	26,456	95,714	76,412
Income from operations	8,902	36,844	32,110	76,246
Other income (expense), net:
Interest income, net	990	156	2,262	184
Change in fair value of preferred stock warrant liability	0	0	0	(3,361)
Other (expense) income, net	(21)	10	(60)	(68)
Total other income (expense), net	969	166	2,202	(3,245)
Income before (benefit) provision for income taxes	9,871	37,010	34,312	73,001
(Benefit) provision for income taxes	(8,628)	2,122	(24,560)	5,918
Net income	18,499	34,888	58,872	67,083
Accretion of redeemable convertible preferred stock	0	0	0	(1,722)
Undistributed earnings attributable to participating securities	0	0	0	(23,959)
Net income attributable to common stockholders - basic	18,499	34,888	58,872	41,402
Net income attributable to common stockholders - diluted	$ 18,499	$ 34,888	$ 58,872	$ 41,402
Net income per share attributable to common stockholders:
Basic (in USD per share)	$ 0.47	$ 0.97	$ 1.52	$ 1.95
Diluted (in USD per share)	$ 0.44	$ 0.86	$ 1.41	$ 1.64
Weighted-average shares used to compute net income per share attributable to common stockholders:
Basic (in shares)	39,259	35,922	38,754	21,195
Diluted (in shares)	41,757	40,708	41,660	25,183

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 18,499	$ 34,888	$ 58,872	$ 67,083
Other comprehensive loss:
Changes in unrealized loss on marketable securities, net of income taxes of $(4), $(2), $6 and $6 for the three and nine months ended September 30, 2017 and 2016, respectively	(4)	(17)	(18)	(17)
Comprehensive income	$ 18,495	$ 34,871	$ 58,854	$ 67,066

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ (4)	$ 6	$ (2)	$ 6

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Redeemable Convertible Preferred Stock
Temporary equity, beginning balance (in shares) at Dec. 31, 2015						24,177
Temporary equity, beginning balance at Dec. 31, 2015						$ 70,780
Beginning balance (in shares) at Dec. 31, 2015		6,669
Beginning balance at Dec. 31, 2015	$ 8,016	$ 1	$ 0	$ 0	$ 8,015
Temporary equity, accretion of preferred stock issuance costs						94
Accretion of preferred stock issuance costs	(94)		(94)
Temporary equity, accretion to redemption value						$ 1,628
Accretion to redemption value	(1,628)		(950)		(678)
Temporary equity, conversion of redeemable convertible preferred stock into common stock upon initial public offering (in shares)						(24,177)
Temporary equity, conversion of redeemable convertible preferred stock into common stock upon initial public offering						$ (72,502)
Conversion of redeemable convertible preferred stock into common stock upon initial public offering (in shares)		24,177
Conversion of redeemable convertible preferred stock into common stock upon initial public offering	72,502	$ 2	72,500
Reclassification of preferred stock warrant liability into additional paid-in capital upon conversion to common stock warrants	6,615		6,615
Issuance of common stock in relation to initial public offering, net of offering costs incurred of $3,824 (in shares)		4,570
Issuance of common stock in relation to initial public offering, net of offering costs incurred of $4,235	93,522	$ 1	93,521
Vesting of restricted common stock (in shares)		64
Exercise of common stock options (in shares)		243
Exercise of common stock options	356		356
Stock-based compensation expense	16,136		16,136
Unrealized losses on marketable securities, net of tax	(17)			(17)
Net income	67,083				67,083
Temporary equity, ending balance (in shares) at Sep. 30, 2016						0
Temporary equity, ending balance at Sep. 30, 2016						$ 0
Ending balance (in shares) at Sep. 30, 2016		35,723
Ending balance at Sep. 30, 2016	262,491	$ 4	188,084	(17)	74,420
Temporary equity, beginning balance (in shares) at Dec. 31, 2016						0
Temporary equity, beginning balance at Dec. 31, 2016						$ 0
Beginning balance (in shares) at Dec. 31, 2016		37,998
Beginning balance at Dec. 31, 2016	$ 434,795	$ 4	295,893	(16)	138,914
Vesting of restricted common stock (in shares)		72
Exercise of common stock options (in shares)	599	599
Exercise of common stock options	$ 2,361		2,361
Vesting of restricted stock units (in shares)		603
Common stock issued under employee stock purchase plan (in shares)		30
Common stock issued under employee stock purchase plan	1,179		1,179
Stock-based compensation expense	17,162		17,162
Unrealized losses on marketable securities, net of tax	(18)			(18)
Net income	58,872				58,872
Temporary equity, ending balance (in shares) at Sep. 30, 2017						0
Temporary equity, ending balance at Sep. 30, 2017						$ 0
Ending balance (in shares) at Sep. 30, 2017		39,302
Ending balance at Sep. 30, 2017	$ 514,351	$ 4	$ 316,595	$ (34)	$ 197,786

CONDENSED CONSOLIDATED STATEME8

CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2016USD ($)
Statement of Stockholders' Equity [Abstract]
Changes in unrealized loss on marketable securities, tax	$ 6
Offering costs incurred	$ 4,235

CONDENSED CONSOLIDATED STATEME9

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 58,872	$ 67,083
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	9,101	6,536
Gain on disposal of property and equipment	(47)	0
Stock-based compensation	17,162	16,136
Deferred income taxes	(23,569)	(5,153)
Other non-cash charges	259	61
Change in fair value of preferred stock warrant liability	0	3,361
Changes in operating assets and liabilities:
Accounts receivable	12,505	(60,489)
Inventory	(18,302)	(1,274)
Prepaid expenses and other current assets	(4,978)	(2,625)
Deferred product costs	(178)	1,788
Restricted cash	1,630	(2,181)
Other assets	(4,658)	(172)
Accounts payable	(9,878)	23,911
Accrued liabilities	6,258	15,999
Deferred revenue	(92)	195
Other long-term liabilities	992	1,193
Net cash provided by operating activities	45,077	64,369
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(10,031)	(12,267)
Purchases of marketable securities	(306,327)	(52,719)
Sales and maturities of marketable securities	177,353	0
Deposits	(52)	(42)
Net cash used in investing activities	(139,057)	(65,028)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of capital lease obligation	0	(34)
Proceeds from initial public offering, net of underwriting discounts and commissions	0	97,757
Payment of public offering costs	(201)	(2,116)
Proceeds from the issuance of common stock under stock-based compensation plans	3,540	356
Net cash provided by financing activities	3,339	95,963
Net (decrease) increase in cash and cash equivalents	(90,641)	95,304
Cash and cash equivalents—Beginning of period	206,402	27,610
Cash and cash equivalents—End of period	115,761	122,914
Supplemental cash flow disclosures:
Cash paid for income taxes, net of refunds	840	2,801
Supplemental disclosure of non-cash investing and financing activities:
Capital expenditures incurred but not yet paid	609	307
Public offering costs incurred but not yet paid	0	946
Accretion of redemption value on redeemable convertible preferred stock	0	1,628
Accretion of redeemable convertible preferred stock issuance costs	0	94
Conversion of redeemable convertible preferred stock into common stock	0	72,502
Reclassification to additional paid-in capital of fair value of preferred stock warrant liability upon conversion to common stock warrants	$ 0	$ 6,615

NATURE OF THE BUSINESS AND OPER

NATURE OF THE BUSINESS AND OPERATIONS	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF THE BUSINESS AND OPERATIONS	NATURE OF THE BUSINESS AND OPERATIONS Acacia Communications, Inc. was incorporated on June 2, 2009 , as a Delaware corporation. Acacia Communications, Inc. and its wholly-owned subsidiaries (the “Subsidiaries”) are collectively referred to as the Company. The Company is a leading provider of high-speed coherent interconnect products that are designed to improve the capacity, performance, intelligence and cost of communications networks relied upon by cloud infrastructure operators and content and communications service providers. The Company’s products include a series of low-power coherent digital signal processors and silicon photonic integrated circuits integrated into families of optical interconnect modules with transmission speeds ranging from 100 to 400 gigabits per second for use in long-haul, metro and inter-data center markets. The Company is also developing optical interconnect modules that will enable transmission speeds of one terabit (1,000 gigabits) per second and above. The Company is headquartered in Maynard, Massachusetts, and has established wholly-owned subsidiaries in North America, Europe and Asia as part of the Company’s global expansion. On May 18, 2016, the Company closed its initial public offering (“IPO”), in which the Company issued and sold 4,570,184 shares of common stock and certain selling stockholders sold an additional 604,816 shares, inclusive of the underwriters’ option to purchase additional shares that was exercised in full. The price per share to the public was $23.00 . The Company received aggregate proceeds of approximately $97.8 million from the IPO, net of underwriters’ discounts and commissions, before deduction of offering expenses of approximately $4.3 million . The Company received no proceeds from the sale of shares by the selling stockholders. Upon the closing of the IPO, all shares of the Company’s outstanding redeemable convertible preferred stock (the “preferred stock”) automatically converted into 24,177,495 shares of common stock. On October 13, 2016, the Company closed a follow-on public offering in which the Company issued and sold 1,210,302 shares of common stock and certain selling stockholders sold an additional 3,289,698 shares. The underwriters’ option to purchase up to an additional 675,000 shares from certain of the selling stockholders was not exercised. The price per share to the public was $100.00 . The Company received aggregate proceeds of $116.8 million from the follow-on offering, net of underwriters’ discounts and commissions, before deduction of offering expenses of approximately $1.2 million . The Company received no proceeds from the sale of shares by the selling stockholders.

BASIS OF PRESENTATION AND SUMMA

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The unaudited condensed consolidated financial statements include the accounts of Acacia Communications, Inc. and its Subsidiaries and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by GAAP for annual financial statements. For further information, these condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016, which was filed with the SEC on February 23, 2017. There have been no significant changes in the Company’s accounting policies from those disclosed in the Annual Report on Form 10-K that have had a material impact on the Company’s condensed consolidated financial statements. The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements as of and for the year ended December 31, 2016 , and in management’s opinion, include all adjustments, consisting of only normal recurring adjustments, necessary for the fair statement of the Company’s condensed consolidated balance sheet as of September 30, 2017 , its condensed consolidated income statements for the three and nine months ended September 30, 2017 and 2016 , its condensed consolidated statements of comprehensive income for the three and nine months ended September 30, 2017 and 2016 , its condensed consolidated statements of redeemable convertible preferred stock and stockholders’ equity for the nine months ended September 30, 2017 and 2016 , and its condensed consolidated statements of cash flows for the nine months ended September 30, 2017 and 2016 . All intercompany balances and transactions have been eliminated in consolidation. The financial data and the other financial information disclosed in the notes to these condensed consolidated financial statements related to these three and nine -month periods are also unaudited. The results of operations for the three and nine months ended September 30, 2017 are not necessarily indicative of the results to be expected for the full fiscal year or any other period. Use of Estimates The preparation of unaudited condensed consolidated financial statements in conformity with 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 unaudited condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Recently Adopted Accounting Pronouncements In May 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 provides clarity about which changes to terms or conditions of a share-based payment award require modification accounting. Specifically, an entity would not apply modification accounting if the fair value, vesting conditions, and classification of the awards are the same immediately before and after the modification. The amendments in ASU 2017-09, effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, were early adopted by the Company in the third quarter of 2017. The amendments will be applied on a prospective basis to awards modified on or after the adoption date, none of which occurred during the third quarter of 2017. Recently Issued Accounting Pronouncements In March 2017, the FASB issued ASU 2017-08, Receivables – Nonrefundable Fees and Other Costs (Topic 310-20): Premium Amortization on Purchased Callable Debt Securities (“ASU 2017-08”). ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium to the earliest call date in order to reduce diversity in practice and provide more decision-useful information. The amendments in ASU 2017-08 are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years with early adoption permitted, and is required to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company does not anticipate that this guidance will have a material impact on its condensed consolidated financial statements because all of the Company’s callable debt securities held at a premium are already amortized to the earliest call date. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 320): Restricted Cash ( “ASU 2016-18” ). ASU 2016-18 will require amounts generally described as restricted cash or restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The amendments in ASU 2016-18 are effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, and must be applied using a retrospective approach with earlier adoption permitted. The Company expects its condensed consolidated statements of cash flows to be impacted by the amount of restricted cash held by the Company in each period. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). ASU 2016-16 requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The amendments in ASU 2016-16 are effective for fiscal years beginning after December 15, 2017, and must be applied using a modified retrospective approach with earlier adoption permitted for annual reporting periods for which financial statements have not yet been issued. The Company does not anticipate that this guidance will have a material impact on its condensed consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 is intended to provide more decision-useful information about expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The main provisions include presenting financial assets measured at amortized cost at the amount expected to be collected, which is net of an allowance for credit losses, and recording credit losses related to available-for-sale securities through an allowance for credit losses. The amendments in ASU 2016-13 are effective for fiscal years beginning after December 15, 2019, and must be applied using a modified retrospective approach with earlier adoption permitted for fiscal years beginning after December 15, 2018. The Company is currently evaluating the impact of this guidance on its condensed consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 will require lessees to recognize a right-of-use asset and lease liability on the balance sheet for virtually all leases. For the income statement, ASU 2016-02 retains a dual model requiring leases to be classified as either operating or financing leases. Operating leases will result in straight-line expense, and financing leases will have a front-loaded expense pattern with an interest expense component. The amendments in ASU 2016-02 are effective for fiscal years beginning after December 15, 2018, and must be applied using a modified retrospective approach with earlier adoption permitted. The Company expects the adoption of ASU 2016-02 will increase both its assets and liabilities presented on its condensed consolidated balance sheets to reflect the right-of-use assets and corresponding lease liabilities, as well as increase its leasing disclosures. The Company is continuing its assessment and review of existing leases, as well as policy and process changes to support the new standard. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), which affects any entity that either enters into contracts with customers to transfer goods and services or enters into contracts for the transfer of nonfinancial assets. ASU 2014-09 will replace most existing revenue recognition guidance in GAAP when it becomes effective. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under the currently effective guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. The new guidance is required to be applied retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying it recognized at the date of initial application. ASU 2014-09 was initially to be effective for annual periods beginning after December 15, 2016, including interim periods within that period. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers , which delays the effective date of ASU 2014-09 by one year and allows for early adoption as of the original effective date. In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations , which clarifies certain principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing , which clarifies certain guidance related to identifying performance obligations and licensing. In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients , which addresses improvements to the guidance on collectability, noncash consideration and completed contracts at transition. In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which addresses clarifications and corrections in various areas, including contract costs and disclosures. The Company has completed its initial evaluation of the impact that ASU 2014-09 could have on its condensed consolidated financial statements. As of September 30, 2017, the Company has not identified any accounting changes related to ASU 2014-09 that would materially impact the amount of its reported revenues as, upon adoption, most revenue will continue to be recognized at a point-in-time when control transfers which is similar to the current revenue recognition model. The Company plans to adopt this guidance on January 1, 2018, using the modified retrospective adoption method applied to those contracts that were not completed as of that date. As the Company finalizes its evaluation, it is also assessing any disclosure requirements and preparing to implement changes to accounting policies, business processes and internal controls to support the new standard.

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
FINANCIAL INSTRUMENTS	FINANCIAL INSTRUMENTS The following tables set forth the Company’s cash, cash equivalents and short- and long-term marketable securities as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 Gross Unrealized Amortized Cost Gains Losses (1) Estimated Fair Value Cash and Cash Equivalents Marketable Securities Cash $ 61,351 $ — $ — $ 61,351 $ 61,351 $ — Money market funds 17,461 — — 17,461 17,461 — Repurchase agreements 25,000 — — 25,000 25,000 — U.S. treasury bonds 2,196 — (2 ) 2,194 — 2,194 Commercial paper 54,520 2 — 54,522 10,498 44,024 Certificates of deposit 25,999 8 (2 ) 26,005 1,000 25,005 Asset-backed securities 26,688 5 (4 ) 26,689 — 26,689 Corporate debt securities 135,292 27 (77 ) 135,242 451 134,791 Total $ 348,507 $ 42 $ (85 ) $ 348,464 $ 115,761 $ 232,703 (1) Losses represent marketable securities that were in loss positions for less than one year. December 31, 2016 Gross Unrealized Amortized Cost Gains Losses (1) Estimated Fair Value Cash and Cash Equivalents Marketable Securities Cash $ 81,230 $ — $ — $ 81,230 $ 81,230 $ — Money market funds 118,174 — — 118,174 118,174 — U.S. treasury bonds 15,017 — (2 ) 15,015 — 15,015 Commercial paper 49,673 — — 49,673 5,997 43,676 Corporate debt securities 46,339 2 (27 ) 46,314 1,001 45,313 Total $ 310,433 $ 2 $ (29 ) $ 310,406 $ 206,402 $ 104,004 (1) Losses represent marketable securities that were in loss positions for less than one year. The proceeds from the sales and maturities of marketable securities, which were primarily reinvested and resulted in realized gains and losses, were as follows (in thousands): Three Months Ended September 30, 2017 Nine Months Ended September 30, 2017 Proceeds from the sales and maturities of marketable securities $ 77,053 $ 177,353 Realized gains $ 3 $ 7 Realized losses $ (1 ) $ (1 ) The contractual maturities of short-term and long-term marketable securities held at September 30, 2017 and December 31, 2016 are as follows (in thousands): September 30, 2017 December 31, 2016 Amortized Cost Basis Aggregate Fair Value Amortized Cost Basis Aggregate Fair Value Due within one year $ 173,395 $ 173,388 $ 104,031 $ 104,004 Due after 1 year through 3 years 59,350 59,315 — — Total $ 232,745 $ 232,703 $ 104,031 $ 104,004 At September 30, 2017 , the Company believed that the unrealized losses on its available-for-sale investments were temporary. The investments with unrealized losses consisted primarily of corporate debt securities. In making the determination that the decline in fair value of these securities was temporary, the Company considered various factors, including, but not limited to: the length of time each security was in an unrealized loss position; the extent to which fair value was less than cost; the financial condition and near-term prospects of the issuers; and the Company’s intent not to sell these securities and the assessment that it is more likely than not that the Company would not be required to sell these securities before the recovery of their amortized cost basis.

INVENTORY

INVENTORY	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
INVENTORY	INVENTORY Inventory consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Raw materials $ 27,554 $ 14,385 Work-in-process 1,476 3,235 Finished goods 20,953 14,061 Inventory $ 49,983 $ 31,681

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT Property and equipment consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Engineering laboratory equipment $ 36,909 $ 31,096 Computer software 1,751 1,381 Computer equipment 3,775 2,572 Furniture and fixtures 2,922 408 Leasehold improvements 2,341 1,032 Construction in progress 2,283 5,954 Total property and equipment 49,981 42,443 Less: Accumulated depreciation (24,891 ) (17,319 ) Property and equipment, net $ 25,090 $ 25,124 Depreciation expense was $3.3 million and $2.7 million for the three months ended September 30, 2017 and 2016 , respectively, and $9.1 million and $6.5 million for the nine months ended September 30, 2017 and 2016 , respectively.

ACCRUED LIABILITIES

ACCRUED LIABILITIES	9 Months Ended
	Sep. 30, 2017
Payables and Accruals [Abstract]
ACCRUED LIABILITIES	ACCRUED LIABILITIES Accrued liabilities consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Employee-related liabilities $ 6,942 $ 6,235 Outsourced foundry services 95 1,811 Goods and services received not invoiced 11,838 9,024 Accrued income taxes 940 670 Accrued manufacturing related expenses 7,982 5,255 Warranty reserve 3,419 2,158 Other accrued liabilities 5,306 4,710 Accrued liabilities $ 36,522 $ 29,863

FAIR VALUE MEASUREMENT

FAIR VALUE MEASUREMENT	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENT	FAIR VALUE MEASUREMENT The Company measures certain financial assets and liabilities at fair value. Fair value is determined based upon the exit price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants, as determined by either the principal market or the most advantageous market. Inputs used in the valuation techniques to derive fair values are classified based on a three-level hierarchy, as follows: Level 1 —Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 —Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets with insufficient volume or infrequent transactions (less active markets), or model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 —Unobservable inputs to the valuation methodology that are significant to the measurement of fair value of assets or liabilities. The Company considers all highly liquid investments purchased with a remaining maturity of three months or less to be cash equivalents. The Company’s cash equivalents consist of money market funds, repurchase agreements, commercial paper, certificates of deposit and corporate debt securities with an original maturity of three months or less. The Company’s investments in money market funds, repurchase agreements, commercial paper, certificates of deposit, asset-backed securities, corporate bonds and U.S. government agency debt securities, which are classified as Level 2 within the fair value hierarchy, were initially valued at the transaction price and subsequently valued at each reporting date utilizing market-observable data. The market-observable data included reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, current spot rates and other industry and economic events. The fair value of these assets measured on a recurring basis was determined using the following inputs as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets: Money market funds $ — $ 17,461 $ — $ 17,461 Repurchase agreements — 25,000 — 25,000 U.S. treasury bonds — 2,194 — 2,194 Commercial paper — 54,522 — 54,522 Certificates of deposit — 26,005 — 26,005 Asset-backed securities — 26,689 — 26,689 Corporate debt securities — 135,242 — 135,242 Total $ — $ 287,113 $ — $ 287,113 December 31, 2016 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets: Money market funds $ — $ 118,174 $ — $ 118,174 U.S. treasury bonds — 15,015 — 15,015 Commercial paper — 49,673 — 49,673 Corporate debt securities — 46,314 — 46,314 Total $ — $ 229,176 $ — $ 229,176 There have been no transfers between fair value measurement levels during the three or nine months ended September 30, 2017 . For certain other financial instruments, including accounts receivable, restricted cash, accounts payable, and other current liabilities, the carrying amounts approximate their fair value due to the relatively short maturity of these balances. Preferred Stock Warrants Prior to the closing of the Company’s IPO, the Company remeasured the fair value of its preferred stock warrants at each balance sheet date. Any changes in fair value were recognized as a component of other income (expense) in the condensed consolidated income statements. The valuation technique used to measure fair value for the Company’s preferred stock warrants, which were considered Level 3 fair value estimates within the fair value hierarchy, was the Black-Scholes option pricing model. The significant unobservable inputs used in the fair value measurement of the Company’s preferred stock warrants was the fair value of the Company’s series B and series C preferred stock. The Company also utilized risk-free interest rate, expected dividend yield, expected volatility and expected term as observable inputs with the fair value of the series B and series C preferred stock in determining the fair value of the preferred stock warrants. There is not a direct interrelationship between the unobservable inputs and the observable inputs. A summary of the changes in the Company’s preferred stock warrant liability measured at fair value using significant unobservable inputs (Level 3) for the nine months ended September 30, 2016 is as follows (in thousands): Nine Months Ended September 30, 2016 Preferred stock warrant liability at beginning of period $ 3,254 Change in fair value 3,361 Reclassification of preferred stock warrant liability to additional paid-in capital upon conversion to common stock warrants $ (6,615 ) Preferred stock warrant liability at end of period $ — The warrants to purchase shares of preferred stock were converted into warrants to purchase shares of common stock upon the closing of the IPO.

STOCK COMPENSATION PLANS

STOCK COMPENSATION PLANS	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK COMPENSATION PLANS	STOCK COMPENSATION PLANS The following table summarizes the classification of stock-based compensation in the condensed consolidated income statements for the three and nine months ended September 30, 2017 and 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Cost of revenue $ 518 $ 504 $ 1,469 $ 1,196 Research and development 3,743 3,782 10,516 9,360 Sales, general and administrative 2,159 2,389 5,177 5,580 Total stock-based compensation $ 6,420 $ 6,675 $ 17,162 $ 16,136 The following table summarizes stock-based compensation expense by award type for the three and nine months ended September 30, 2017 and 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Stock options $ 648 $ 623 $ 1,969 $ 1,391 Restricted stock awards 29 29 87 76 Restricted stock units 5,412 5,740 14,224 14,235 Employee stock purchase plan 331 283 882 434 Total stock-based compensation $ 6,420 $ 6,675 $ 17,162 $ 16,136 Stock Options A summary of stock option activity under the Company’s equity incentive plans for the nine months ended September 30, 2017 is as follows: Number of Options (in thousands) Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2016 2,354 $ 7.10 7.4 $ 129,288 Granted — Exercised (599 ) $ 3.95 $ 30,051 Cancelled (11 ) $ 8.81 Outstanding at September 30, 2017 1,744 $ 8.17 6.9 $ 69,095 Vested and expected to vest at: September 30, 2017 1,744 $ 8.17 6.9 $ 69,095 December 31, 2016 2,354 $ 7.10 7.4 $ 129,288 Exercisable at: September 30, 2017 879 $ 4.63 6.0 $ 37,626 December 31, 2016 975 $ 1.78 6.1 $ 58,458 As of September 30, 2017 and December 31, 2016 , there was $5.5 million and $7.6 million , respectively, of unrecognized compensation cost related to unvested common stock options, which is expected to be recognized over weighted-average periods of 2.4 years and 3.1 years, respectively. The weighted-average grant date fair value of stock options granted during the three and nine months ended September 30, 2016 was $34.82 and $10.97 , respectively. No stock options were granted by the Company during the three or nine months ended September 30, 2017 . Restricted Stock Units During the nine months ended September 30, 2017 , the Company granted 537,000 restricted stock units (“RSUs”) to employees and executives under the 2016 Equity Incentive Plan that vest upon the satisfaction of a service condition, generally over four years. The cost of any RSUs with only a service condition is determined using the fair value of the Company’s common stock on the date of grant, and compensation is recognized on a straight-line basis over the requisite vesting period. During the nine months ended September 30, 2017 , the Company granted 461,000 RSUs to executive officers that include a market condition and a performance condition in addition to a service condition (“performance-based RSUs” or “PRSUs”). Each PRSU represents the right to receive one share of the Company’s common stock when and if the applicable vesting conditions are satisfied. The number of PRSUs that are subject to the service condition is determined based on the achievement of certain market and performance objectives over a two -year period running from January 1, 2017 through December 31, 2018 (the “Earned PRSUs”). Thirty-three percent of any Earned PRSUs will vest on the later of (i) March 17, 2019 and (ii) the date that the number of Earned PRSUs is determined by the Compensation Committee after December 31, 2018. Thereafter, an additional 33% of the Earned PRSUs will vest on March 17, 2020 and the remaining 34% of the Earned PRSUs will vest on March 17, 2021 . Vesting of Earned PRSUs is subject to the applicable officer’s continued provision of services to the Company through the applicable vesting date. The number of PRSUs that become Earned PRSUs will be determined based on the extent to which the Company achieves (i) a revenue growth objective, based on the compound annual growth rate of the Company’s total revenue by measuring the Company’s revenue for fiscal year 2018 against the Company’s revenue for fiscal year 2016 (the “Revenue Growth Objective”), and/or (ii) a stock price objective during the two -year period (the “Stock Price Objective”). If neither the Revenue Growth Objective nor the Stock Price Objective is achieved, none of the PRSUs will become Earned PRSUs. Any PRSUs that do not become Earned PRSUs shall be forfeited once the number of Earned PRSUs is determined by the Compensation Committee after December 31, 2018. For the PRSUs, the related stock-based compensation expense is amortized using the accelerated method over the vesting period of four years. The Company estimates the fair value of the PRSUs using management’s best estimate of whether it is probable or not probable that the Revenue Growth Objective will be satisfied using the most currently available projections of future revenue performance, which is reassessed at each reporting period. Changes in the subjective and probability-based assumptions can materially affect the estimate of fair value of stock-based compensation and consequently, the related amount recognized in the Company’s condensed consolidated income statements. The Company estimated the fair value of the PRSUs using a Monte Carlo valuation model on the date of grant, using the following assumptions: Risk-free interest rate 1.3% Expected dividend yield None Expected volatility 58.3% Expected term (in years) 1.8 Grant date fair value of underlying shares $40.38 - $55.02 As soon as practicable following each vesting date of RSUs, including PRSUs, the Company will issue to the holder of the RSUs the number of shares of common stock equal to the aggregate number of RSUs that have vested. Notwithstanding the foregoing, the Company may, in its sole discretion, in lieu of issuing shares of common stock to the holder of the RSUs, pay the holder an amount in cash equal to the fair market value of such shares of common stock. To date, the Company has not settled any vested RSUs with cash. A summary of the changes in the Company’s RSUs during the nine months ended September 30, 2017 is as follows: RSUs (in thousands) Weighted-Average Grant Date Fair Value Outstanding at December 31, 2016 2,034 $ 21.09 Granted 998 $ 54.20 Vested (603 ) $ 19.17 Cancelled (8 ) $ 29.35 Outstanding at September 30, 2017 2,421 $ 35.19 The granted amount includes the 461,000 PRSUs which is the maximum number that were granted to executives during the nine months ended September 30, 2017 . As of September 30, 2017 and December 31, 2016 , there was $51.9 million and $32.1 million , respectively, of total unrecognized compensation cost related to unvested RSUs, which is expected to be recognized over weighted-average periods of 3.1 years and 3.4 years, respectively.

NET INCOME PER SHARE ATTRIBUTAB

NET INCOME PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
NET INCOME PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS	NET INCOME PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS Basic and diluted net income per share attributable to common stockholders is presented in conformity with the two-class method required for participating securities. The Company considers its preferred stock to be participating securities. In the event a cash dividend is paid on common stock, the holders of preferred stock are also entitled to a proportionate share of any such dividend as if they were holders of common stock (on an as-if converted basis). The holders of the preferred stock do not have a contractual obligation to share in losses. In accordance with the two-class method, earnings allocated to these participating securities and the related number of outstanding shares of the participating securities, which include contractual participation rights in undistributed earnings, have been excluded from the computation of basic and diluted net income per share attributable to common stockholders. As a result of the conversion of preferred stock on May 18, 2016, no earnings were allocated to participating securities during the three and nine months ended September 30, 2017 or the three months ended September 30, 2016 . The following table sets forth the computation of the Company’s basic and diluted net income per share attributable to common stockholders (in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Numerator: Net income $ 18,499 $ 34,888 $ 58,872 $ 67,083 Less: preferred stock accretion — — — (1,722 ) Less: undistributed earnings attributable to participating securities — — — (23,959 ) Net income attributable to common stockholders - basic and diluted $ 18,499 $ 34,888 $ 58,872 $ 41,402 Denominator: Weighted-average shares used to compute net income per share attributable to common stockholders - basic 39,259 35,922 38,754 21,195 Dilutive effect of stock options, unvested restricted stock and restricted stock units, preferred stock warrants, and employee stock purchase plan 2,498 4,786 2,906 3,988 Weighted-average shares used to compute net income per share attributable to common stockholders - diluted 41,757 40,708 41,660 25,183 Net income per share attributable to common stockholders Basic $ 0.47 $ 0.97 $ 1.52 $ 1.95 Diluted $ 0.44 $ 0.86 $ 1.41 $ 1.64 The following common stock equivalents (in thousands) were excluded from the computation of diluted net income per share for the periods presented because including them would have been antidilutive: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Options to purchase common stock 90 17 90 30 Unvested restricted stock units and awards 545 21 424 16 Preferred stock warrants — — — 245 Employee stock purchase plan 48 — — — As discussed further in Note 8, in March 2017, the Company granted 461,000 PRSUs to executives that include market, performance and service conditions. As the market and performance criteria associated with the vesting of those awards have not been satisfied as of September 30, 2017 , the Company has excluded those shares from the table above and the calculation of diluted net income per share attributable to common stockholders.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Leases The Company’s principal facilities are located in Maynard, Massachusetts and Holmdel, New Jersey and are leased by the Company under non-cancelable operating leases that expire in February 2025, with respect to the Massachusetts facility, and December 2021, with respect to the New Jersey facility. The Company also leases office space in various locations with expiration dates between 2018 and 2022 . Several of the lease agreements include leasehold improvement incentives, escalating lease payments, renewal provisions and other provisions which require the Company to pay taxes, insurance and maintenance costs. All of the Company’s facility leases are accounted for as operating leases. Rent expense is recorded over each respective lease term on a straight-line basis. Rent expense was $1.2 million and $0.3 million for the three months ended September 30, 2017 and 2016 , respectively, and $3.9 million and $0.9 million for the nine months ended September 30, 2017 and 2016 , respectively. Future minimum lease payments due under these non-cancelable lease agreements as of September 30, 2017 , are as follows (in thousands): Amounts Remaining 2017 $ 869 2018 3,342 2019 3,306 2020 3,335 2021 3,244 Thereafter 7,835 Total $ 21,931 As of September 30, 2017 , the Company was committed to approximately $0.9 million for additional construction build-out at the Maynard facility. Warranties The Company’s standard warranty obligation to its customers provides for repair or replacement of a defective product at the Company’s discretion for a period of time following purchase, generally between 12 and 24 months . Factors that affect the warranty obligation include product failure rates, material usage, and service delivery costs incurred in correcting product failures. In addition, from time to time, specific warranty accruals may be made if unforeseen technical problems arise. The estimated cost associated with fulfilling the Company’s warranty obligation to customers is recorded in cost of revenue. Changes in the Company’s product warranty liability, which is included as a component of accrued liabilities on the condensed consolidated balance sheets, are set forth in the table below (in thousands). The reserves below do not include reserves established as a result of the manufacturing process quality issue described below under the heading “Manufacturing Process Quality Reserve.” Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Warranty reserve, beginning of period $ 4,859 $ 1,306 $ 2,158 $ 763 Provisions made to warranty reserve during the period 3,483 2,334 9,456 4,120 Charges against warranty reserve during the period (4,923 ) (1,531 ) (8,195 ) (2,774 ) Warranty reserve, end of period $ 3,419 $ 2,109 $ 3,419 $ 2,109 Manufacturing Process Quality Reserve In May 2017, the Company announced a quality issue at one of its three contract manufacturers that affected a portion of the units manufactured by the contract manufacturer over an approximate four month period, which at that time was estimated at approximately 1,300 AC400 units and 5,100 CFP units (the “Quality Issue”). Subsequently, the estimate of the potentially impacted units was increased to approximately 1,900 AC400 units and 7,000 CFP units, to include units manufactured but not yet shipped to customers, and based on an evaluation of such units, the Company established reserves to cover anticipated costs, including cost estimates for product repairs, rework of component inventory with the contract manufacturer and rescreening costs as a result of the Quality Issue. The Quality Issue warranty reserve of $1.1 million was recorded as a component of accrued liabilities in the Company’s condensed consolidated balance sheets as of September 30, 2017 , and an additional $5.5 million was reserved against estimated affected inventory on-hand at the contract manufacturer and in-transit returns as of September 30, 2017 . As compared to June 30, 2017, although the Company’s estimate of the number of potentially impacted units increased, better than anticipated testing data resulted in a decrease to the reserve. The Company’s estimates of the Quality Issue costs are subject to further change as customers continue to return potentially impacted units and final testing is performed. Legal Contingencies On January 22, 2016, ViaSat, Inc. filed a suit against the Company alleging, among other things, breach of contract, breach of the implied covenant of good faith and fair dealing and misappropriation of trade secrets. On February 19, 2016, the Company responded to ViaSat’s suit and alleged counterclaims against ViaSat including, among other things, patent misappropriation, breach of contract, breach of the implied covenant of good faith and fair dealing, misappropriation of trade secrets and unfair competition, which ViaSat denied in its response filed March 16, 2016. The Company is continuing to evaluate ViaSat’s claims, but based on the information available to the Company today, the Company currently believes that this suit will not have a material adverse effect on the Company’s business or its condensed consolidated financial position, results of operations or cash flows. On July 28, 2017, the Company filed a suit against ViaSat asserting commercial disparagement, libel, slander of title, unfair competition, intentional interference with advantageous relations and intentional interference with contractual relations. Both lawsuits are still pending and discovery is ongoing. In August and September 2017, three purported securities class action complaints were filed in the U.S. District Court for the District of Massachusetts against the Company and certain of its executive officers (Murugesan Shanmugaraj and John Gavin). The complaints are captioned Tharp v. Acacia Communications, Inc., et al. , Case No. 1:17-cv-11504 (D. Mass.), filed August 14, 2017; Zhang v. Acacia Communications, Inc., et al. , Case No. 1:17-cv-11518 (D. Mass.), filed August 16, 2017; and Kebler v. Acacia Communications, Inc., et al. , Case No. 1:17-cv-11695 (D. Mass.), filed September 7, 2017. Each complaint purports to be brought on behalf of an alleged class of those who purchased the Company’s securities between August 11, 2016 and July 13, 2017, and alleges that the defendants violated Sections 10(b) and/or 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder by making allegedly false and/or misleading statements regarding, among other matters, demand for the Company’s products, the Company’s financial guidance, and/or the Company’s quality control process as it relates to the Quality Issue. Each complaint seeks, among other relief, unspecified compensatory damages, attorneys’ fees, and costs. On October 13, 2017, a fourth purported securities class action complaint was filed in the United States District Court for the District of Massachusetts against the Company, certain of its directors and executive officers (Murugesan Shanmugaraj, John Gavin, Francis Murphy, Eric Swanson, Peter Chung, Benny Mikkelsen, Stan Reiss, John Ritchie, Vincent Roche, Mehrdad Givehchi, John Lomedico, Bhupendra Shah and Christian Rasmussen), certain persons or entities that sold the Company’s common stock in the Company’s October 2016 follow-on public offering, and the underwriters of such offering, captioned Rollhaus v. Acacia Communications, Inc., et al. , Case No. 17-cv-11988 (D. Mass). The complaint purports to be brought on behalf of an alleged class of those who purchased the Company’s common stock pursuant to or traceable to the offering, and alleges that the defendants violated Sections 11, 12(a)(2) and/or 15 of the Securities Act of 1933 by making allegedly false and/or misleading statements regarding, among other matters, demand for the Company’s products, the Company’s financial guidance, and/or the Company’s quality control process as it relates to the Quality Issue. The complaint seeks, among other relief, unspecified compensatory damages, rescission, attorneys’ fees, and costs. The Company intends to engage in a vigorous defense of the class action lawsuits described above. However, the Company is unable to predict the ultimate outcome of these proceedings, and, therefore cannot estimate possible losses or ranges of losses, if any, or the materiality of any such losses. An unfavorable resolution of these matters in any reporting period may have a material adverse effect on the Company’s results of operations and cash flows for that period. In addition, the timing of the final resolution of these proceedings is uncertain. The Company will incur litigation and other expenses as a result of these proceedings, which could have a material impact on the Company’s business, condensed consolidated financial position, results of operations, and cash flows. In addition, from time to time the Company may become involved in legal proceedings or be subject to claims arising in the ordinary course of business. Although the results of litigation and claims cannot be predicted with certainty, the Company currently believes that the final outcome of these ordinary course matters will not have a material adverse effect on the Company’s business or its condensed consolidated financial position, results of operations or cash flows. Regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources and other factors. Indemnification In the ordinary course of business, the Company enters into various agreements containing standard indemnification provisions. The Company’s indemnification obligations under such provisions are typically in effect from the date of execution of the applicable agreement through the end of the applicable statute of limitations. During the three and nine months ended September 30, 2017 and 2016 , the Company did not experience any losses related to these indemnification obligations. The Company does not expect significant claims related to these indemnification obligations, and consequently, has concluded that the fair value of these obligations is not material. Accordingly, as of September 30, 2017 and December 31, 2016 , no amounts have been accrued related to such indemnification provisions.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company is subject to income tax in the United States as well as other tax jurisdictions in which it conducts business. Earnings from non-U.S. activities are subject to local country income tax. The Company does not provide for federal income taxes on the undistributed earnings of its foreign subsidiaries as such earnings are reinvested indefinitely. The Company’s tax provision for interim periods is determined using an estimate of its annual effective tax rate, adjusted for discrete items arising in that quarter. In each quarter, the Company updates its estimate of the annual effective tax rate, and if the estimated annual tax rate changes, the Company makes a cumulative adjustment in that quarter. The Company’s quarterly tax provision, and its quarterly estimate of its annual effective tax rate, are subject to significant volatility due to several factors, including the Company’s ability to accurately predict its pre-tax income and loss in multiple jurisdictions, as well as the portions of stock-based compensation that will either not generate tax benefits or the tax benefit is unpredictable and reflected when realized by employees. For the three months ended September 30, 2017 , the Company recorded a benefit for income taxes of $8.6 million as compared to a tax provision of $2.1 million for the three months ended September 30, 2016 , resulting in an effective tax rate of (87.4)% and 5.7% for the three months ended September 30, 2017 and 2016, respectively. For the nine months ended September 30, 2017 , the Company recorded a benefit from income taxes of $24.6 million as compared to a tax provision of $5.9 million for the nine months ended September 30, 2016 , resulting in an effective tax rate of (71.6)% and 8.1% for the nine months ended September 30, 2017 and 2016, respectively. The benefits for income taxes recorded in the three and nine months ended September 30, 2017 are mainly due to the favorable effect of foreign statutory tax rates applicable to income earned outside the United States under the Company’s corporate structure and the recognition of U.S. excess tax benefits from the taxable compensation on share-based awards. The Company’s historical provision for income taxes is not necessarily reflective of its future results of operations. As of September 30, 2017 and December 31, 2016 , the Company identified $4.6 million and $3.1 million , respectively, of gross uncertain tax positions. Included in those balances as of September 30, 2017 and December 31, 2016 are $2.5 million and $1.5 million , respectively, of tax benefits that, if recognized, would impact the effective tax rate. These have been accrued for as long-term liabilities on the Company’s condensed consolidated balance sheets. The Company’s existing tax positions will continue to generate an increase in unrecognized tax benefits in subsequent periods. The Company’s policy is to record interest and penalties related to unrecognized tax benefits as income tax expense. During the three and nine months ended September 30, 2017 and 2016 , the amounts recorded related to the accrual of interest and penalties were immaterial in each period.

SEGMENT INFORMATION AND GEOGRAP

SEGMENT INFORMATION AND GEOGRAPHIC DATA	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
SEGMENT INFORMATION AND GEOGRAPHIC DATA	SEGMENT INFORMATION AND GEOGRAPHIC DATA The Company operates as one operating segment. Operating segments are defined as components of an enterprise for which separate financial information is regularly evaluated by the chief operating decision maker (“CODM”), which is the Company’s president and chief executive officer, in deciding how to allocate resources and assess performance. The Company’s CODM evaluates the Company’s financial information and resources and assesses the performance of these resources on a consolidated basis. Since the Company operates in one operating segment, all required financial segment information can be found in the condensed consolidated financial statements. Revenue by geographic region, based on ship-to destinations, was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 United States $ 11,333 $ 25,644 $ 47,561 $ 65,660 China 37,234 55,665 123,583 143,017 Germany 21,171 37,333 43,786 82,054 Thailand 15,975 5,255 32,694 14,251 Other 19,285 11,407 50,939 31,003 Total revenue $ 104,998 $ 135,304 $ 298,563 $ 335,985 Total long-lived assets by geographic region consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 United States $ 16,575 $ 14,026 China 1,275 2,235 Thailand 6,680 8,070 Other 560 793 Total long-lived assets $ 25,090 $ 25,124

CONCENTRATIONS OF RISK

CONCENTRATIONS OF RISK	9 Months Ended
	Sep. 30, 2017
Risks and Uncertainties [Abstract]
CONCENTRATIONS OF RISK	CONCENTRATIONS OF RISK Customer Concentration Customers with revenue equal to or greater than 10% of total revenue for the three and nine months ended September 30, 2017 and 2016 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 A 31 % 28 % 34 % 34 % B 16 % 35 % 15 % 28 % C 15 % * 11 % * D 13 % * * * * Less than 10% of revenue in the period indicated Customers that accounted for equal to or greater than 10% of accounts receivable at September 30, 2017 and December 31, 2016 were as follows: September 30, 2017 December 31, 2016 A 29 % 26 % B * 19 % C 24 % 15 % D 12 % * * Less than 10% of accounts receivable at the date indicated Supplier Concentration The Company’s most significant vendor spending is related to purchases from contract manufacturers and component suppliers located in Japan, China, Thailand and the United States, from which the Company purchases a substantial portion of its inventory. For the three and nine months ended September 30, 2017 and 2016 , total purchases from each of the suppliers was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 W * * 25 % * X 20 % 42 % 22 % 43 % Y 47 % 27 % 32 % 20 % Z * 18 % 15 % 19 % * Less than 10% of total purchases in the period indicated The Company also outsources certain engineering projects to a vendor located in the United States. During the three months ended September 30, 2017 and 2016 , the Company incurred 25% and 16% , respectively, of its total research and development costs with the U.S. foundry. During the nine months ended September 30, 2017 and 2016 , the Company incurred 17% of its total research and development costs with the U.S. foundry.

RELATED PARTIES

RELATED PARTIES	9 Months Ended
	Sep. 30, 2017
Related Party Transactions [Abstract]
RELATED PARTIES	RELATED PARTIES One of the members of the Company’s Board of Directors, Vincent Roche, is also the President and Chief Executive Officer and a member of the board of directors of Analog Devices, Inc. (“ADI”). The Company, through its contract manufacturers, periodically purchases supplies from ADI pursuant to purchase orders negotiated on an arm’s length basis between ADI and the Company’s contract manufacturers at prevailing prices. These purchased supplies are used as content in certain of the Company’s manufactured products. During the three and nine months ended September 30, 2017 and 2016, the Company’s contract manufacturers made purchases from ADI of approximately $1.4 million , $3.5 million , $1.5 million , and $3.3 million , respectively.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On October 13, 2017, a fourth purported securities class action complaint was filed in the United States District Court for the District of Massachusetts against the Company, certain of the Company’s directors and executive officers and others on behalf of an alleged class of purchasers of the Company’s securities. Refer to Note 10 for additional details of this action.

BASIS OF PRESENTATION AND SUM25

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of unaudited condensed consolidated financial statements in conformity with 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 unaudited condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Recently Adopted and Recently Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In May 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 provides clarity about which changes to terms or conditions of a share-based payment award require modification accounting. Specifically, an entity would not apply modification accounting if the fair value, vesting conditions, and classification of the awards are the same immediately before and after the modification. The amendments in ASU 2017-09, effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, were early adopted by the Company in the third quarter of 2017. The amendments will be applied on a prospective basis to awards modified on or after the adoption date, none of which occurred during the third quarter of 2017. Recently Issued Accounting Pronouncements In March 2017, the FASB issued ASU 2017-08, Receivables – Nonrefundable Fees and Other Costs (Topic 310-20): Premium Amortization on Purchased Callable Debt Securities (“ASU 2017-08”). ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium to the earliest call date in order to reduce diversity in practice and provide more decision-useful information. The amendments in ASU 2017-08 are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years with early adoption permitted, and is required to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company does not anticipate that this guidance will have a material impact on its condensed consolidated financial statements because all of the Company’s callable debt securities held at a premium are already amortized to the earliest call date. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 320): Restricted Cash ( “ASU 2016-18” ). ASU 2016-18 will require amounts generally described as restricted cash or restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The amendments in ASU 2016-18 are effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years, and must be applied using a retrospective approach with earlier adoption permitted. The Company expects its condensed consolidated statements of cash flows to be impacted by the amount of restricted cash held by the Company in each period. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). ASU 2016-16 requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The amendments in ASU 2016-16 are effective for fiscal years beginning after December 15, 2017, and must be applied using a modified retrospective approach with earlier adoption permitted for annual reporting periods for which financial statements have not yet been issued. The Company does not anticipate that this guidance will have a material impact on its condensed consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 is intended to provide more decision-useful information about expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The main provisions include presenting financial assets measured at amortized cost at the amount expected to be collected, which is net of an allowance for credit losses, and recording credit losses related to available-for-sale securities through an allowance for credit losses. The amendments in ASU 2016-13 are effective for fiscal years beginning after December 15, 2019, and must be applied using a modified retrospective approach with earlier adoption permitted for fiscal years beginning after December 15, 2018. The Company is currently evaluating the impact of this guidance on its condensed consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 will require lessees to recognize a right-of-use asset and lease liability on the balance sheet for virtually all leases. For the income statement, ASU 2016-02 retains a dual model requiring leases to be classified as either operating or financing leases. Operating leases will result in straight-line expense, and financing leases will have a front-loaded expense pattern with an interest expense component. The amendments in ASU 2016-02 are effective for fiscal years beginning after December 15, 2018, and must be applied using a modified retrospective approach with earlier adoption permitted. The Company expects the adoption of ASU 2016-02 will increase both its assets and liabilities presented on its condensed consolidated balance sheets to reflect the right-of-use assets and corresponding lease liabilities, as well as increase its leasing disclosures. The Company is continuing its assessment and review of existing leases, as well as policy and process changes to support the new standard. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), which affects any entity that either enters into contracts with customers to transfer goods and services or enters into contracts for the transfer of nonfinancial assets. ASU 2014-09 will replace most existing revenue recognition guidance in GAAP when it becomes effective. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under the currently effective guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. The new guidance is required to be applied retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying it recognized at the date of initial application. ASU 2014-09 was initially to be effective for annual periods beginning after December 15, 2016, including interim periods within that period. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers , which delays the effective date of ASU 2014-09 by one year and allows for early adoption as of the original effective date. In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations , which clarifies certain principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing , which clarifies certain guidance related to identifying performance obligations and licensing. In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients , which addresses improvements to the guidance on collectability, noncash consideration and completed contracts at transition. In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which addresses clarifications and corrections in various areas, including contract costs and disclosures. The Company has completed its initial evaluation of the impact that ASU 2014-09 could have on its condensed consolidated financial statements. As of September 30, 2017, the Company has not identified any accounting changes related to ASU 2014-09 that would materially impact the amount of its reported revenues as, upon adoption, most revenue will continue to be recognized at a point-in-time when control transfers which is similar to the current revenue recognition model. The Company plans to adopt this guidance on January 1, 2018, using the modified retrospective adoption method applied to those contracts that were not completed as of that date. As the Company finalizes its evaluation, it is also assessing any disclosure requirements and preparing to implement changes to accounting policies, business processes and internal controls to support the new standard.

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of Cash, Cash Equivalents and Short- and Long-term Marketable Securities	The following tables set forth the Company’s cash, cash equivalents and short- and long-term marketable securities as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 Gross Unrealized Amortized Cost Gains Losses (1) Estimated Fair Value Cash and Cash Equivalents Marketable Securities Cash $ 61,351 $ — $ — $ 61,351 $ 61,351 $ — Money market funds 17,461 — — 17,461 17,461 — Repurchase agreements 25,000 — — 25,000 25,000 — U.S. treasury bonds 2,196 — (2 ) 2,194 — 2,194 Commercial paper 54,520 2 — 54,522 10,498 44,024 Certificates of deposit 25,999 8 (2 ) 26,005 1,000 25,005 Asset-backed securities 26,688 5 (4 ) 26,689 — 26,689 Corporate debt securities 135,292 27 (77 ) 135,242 451 134,791 Total $ 348,507 $ 42 $ (85 ) $ 348,464 $ 115,761 $ 232,703 (1) Losses represent marketable securities that were in loss positions for less than one year. December 31, 2016 Gross Unrealized Amortized Cost Gains Losses (1) Estimated Fair Value Cash and Cash Equivalents Marketable Securities Cash $ 81,230 $ — $ — $ 81,230 $ 81,230 $ — Money market funds 118,174 — — 118,174 118,174 — U.S. treasury bonds 15,017 — (2 ) 15,015 — 15,015 Commercial paper 49,673 — — 49,673 5,997 43,676 Corporate debt securities 46,339 2 (27 ) 46,314 1,001 45,313 Total $ 310,433 $ 2 $ (29 ) $ 310,406 $ 206,402 $ 104,004 (1) Losses represent marketable securities that were in loss positions for less than one year.
Proceeds from Sales and Maturities of Marketable Securities	The proceeds from the sales and maturities of marketable securities, which were primarily reinvested and resulted in realized gains and losses, were as follows (in thousands): Three Months Ended September 30, 2017 Nine Months Ended September 30, 2017 Proceeds from the sales and maturities of marketable securities $ 77,053 $ 177,353 Realized gains $ 3 $ 7 Realized losses $ (1 ) $ (1 )
Contractual Maturities of Short-term and Long-Term Marketable Securities Held	The contractual maturities of short-term and long-term marketable securities held at September 30, 2017 and December 31, 2016 are as follows (in thousands): September 30, 2017 December 31, 2016 Amortized Cost Basis Aggregate Fair Value Amortized Cost Basis Aggregate Fair Value Due within one year $ 173,395 $ 173,388 $ 104,031 $ 104,004 Due after 1 year through 3 years 59,350 59,315 — — Total $ 232,745 $ 232,703 $ 104,031 $ 104,004

INVENTORY (Tables)

INVENTORY (Tables)	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Raw materials $ 27,554 $ 14,385 Work-in-process 1,476 3,235 Finished goods 20,953 14,061 Inventory $ 49,983 $ 31,681

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Engineering laboratory equipment $ 36,909 $ 31,096 Computer software 1,751 1,381 Computer equipment 3,775 2,572 Furniture and fixtures 2,922 408 Leasehold improvements 2,341 1,032 Construction in progress 2,283 5,954 Total property and equipment 49,981 42,443 Less: Accumulated depreciation (24,891 ) (17,319 ) Property and equipment, net $ 25,090 $ 25,124

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2017
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Employee-related liabilities $ 6,942 $ 6,235 Outsourced foundry services 95 1,811 Goods and services received not invoiced 11,838 9,024 Accrued income taxes 940 670 Accrued manufacturing related expenses 7,982 5,255 Warranty reserve 3,419 2,158 Other accrued liabilities 5,306 4,710 Accrued liabilities $ 36,522 $ 29,863

FAIR VALUE MEASUREMENT (Tables)

FAIR VALUE MEASUREMENT (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Assets Measured at Fair Value on Recurring Basis	The fair value of these assets measured on a recurring basis was determined using the following inputs as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets: Money market funds $ — $ 17,461 $ — $ 17,461 Repurchase agreements — 25,000 — 25,000 U.S. treasury bonds — 2,194 — 2,194 Commercial paper — 54,522 — 54,522 Certificates of deposit — 26,005 — 26,005 Asset-backed securities — 26,689 — 26,689 Corporate debt securities — 135,242 — 135,242 Total $ — $ 287,113 $ — $ 287,113 December 31, 2016 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Assets: Money market funds $ — $ 118,174 $ — $ 118,174 U.S. treasury bonds — 15,015 — 15,015 Commercial paper — 49,673 — 49,673 Corporate debt securities — 46,314 — 46,314 Total $ — $ 229,176 $ — $ 229,176
Summary of Changes in the Preferred Stock Warrant Liability Measured at Fair Value Using Significant Unobservable Inputs (Level 3)	A summary of the changes in the Company’s preferred stock warrant liability measured at fair value using significant unobservable inputs (Level 3) for the nine months ended September 30, 2016 is as follows (in thousands): Nine Months Ended September 30, 2016 Preferred stock warrant liability at beginning of period $ 3,254 Change in fair value 3,361 Reclassification of preferred stock warrant liability to additional paid-in capital upon conversion to common stock warrants $ (6,615 ) Preferred stock warrant liability at end of period $ —

STOCK COMPENSATION PLANS (Table

STOCK COMPENSATION PLANS (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Classification of Stock-based Compensation	The following table summarizes the classification of stock-based compensation in the condensed consolidated income statements for the three and nine months ended September 30, 2017 and 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Cost of revenue $ 518 $ 504 $ 1,469 $ 1,196 Research and development 3,743 3,782 10,516 9,360 Sales, general and administrative 2,159 2,389 5,177 5,580 Total stock-based compensation $ 6,420 $ 6,675 $ 17,162 $ 16,136
Schedule of Stock-Based Compensation Expense by Award Type	The following table summarizes stock-based compensation expense by award type for the three and nine months ended September 30, 2017 and 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Stock options $ 648 $ 623 $ 1,969 $ 1,391 Restricted stock awards 29 29 87 76 Restricted stock units 5,412 5,740 14,224 14,235 Employee stock purchase plan 331 283 882 434 Total stock-based compensation $ 6,420 $ 6,675 $ 17,162 $ 16,136
Stock Option Activity	A summary of stock option activity under the Company’s equity incentive plans for the nine months ended September 30, 2017 is as follows: Number of Options (in thousands) Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2016 2,354 $ 7.10 7.4 $ 129,288 Granted — Exercised (599 ) $ 3.95 $ 30,051 Cancelled (11 ) $ 8.81 Outstanding at September 30, 2017 1,744 $ 8.17 6.9 $ 69,095 Vested and expected to vest at: September 30, 2017 1,744 $ 8.17 6.9 $ 69,095 December 31, 2016 2,354 $ 7.10 7.4 $ 129,288 Exercisable at: September 30, 2017 879 $ 4.63 6.0 $ 37,626 December 31, 2016 975 $ 1.78 6.1 $ 58,458
Weighted-Average Assumptions Used to Estimate Fair Value	The Company estimated the fair value of the PRSUs using a Monte Carlo valuation model on the date of grant, using the following assumptions: Risk-free interest rate 1.3% Expected dividend yield None Expected volatility 58.3% Expected term (in years) 1.8 Grant date fair value of underlying shares $40.38 - $55.02
Summary of Changes in Company's RSU	A summary of the changes in the Company’s RSUs during the nine months ended September 30, 2017 is as follows: RSUs (in thousands) Weighted-Average Grant Date Fair Value Outstanding at December 31, 2016 2,034 $ 21.09 Granted 998 $ 54.20 Vested (603 ) $ 19.17 Cancelled (8 ) $ 29.35 Outstanding at September 30, 2017 2,421 $ 35.19

NET INCOME PER SHARE ATTRIBUT32

NET INCOME PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Income Per Share Attributable to Common Stockholders	The following table sets forth the computation of the Company’s basic and diluted net income per share attributable to common stockholders (in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Numerator: Net income $ 18,499 $ 34,888 $ 58,872 $ 67,083 Less: preferred stock accretion — — — (1,722 ) Less: undistributed earnings attributable to participating securities — — — (23,959 ) Net income attributable to common stockholders - basic and diluted $ 18,499 $ 34,888 $ 58,872 $ 41,402 Denominator: Weighted-average shares used to compute net income per share attributable to common stockholders - basic 39,259 35,922 38,754 21,195 Dilutive effect of stock options, unvested restricted stock and restricted stock units, preferred stock warrants, and employee stock purchase plan 2,498 4,786 2,906 3,988 Weighted-average shares used to compute net income per share attributable to common stockholders - diluted 41,757 40,708 41,660 25,183 Net income per share attributable to common stockholders Basic $ 0.47 $ 0.97 $ 1.52 $ 1.95 Diluted $ 0.44 $ 0.86 $ 1.41 $ 1.64
Summary of Common Stock Equivalents Excluded from Computation of Diluted Net Income Per Share	The following common stock equivalents (in thousands) were excluded from the computation of diluted net income per share for the periods presented because including them would have been antidilutive: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Options to purchase common stock 90 17 90 30 Unvested restricted stock units and awards 545 21 424 16 Preferred stock warrants — — — 245 Employee stock purchase plan 48 — — —

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Future Annual Minimum Lease Payments	Future minimum lease payments due under these non-cancelable lease agreements as of September 30, 2017 , are as follows (in thousands): Amounts Remaining 2017 $ 869 2018 3,342 2019 3,306 2020 3,335 2021 3,244 Thereafter 7,835 Total $ 21,931
Schedule of Changes in Product Warrant Liability	Changes in the Company’s product warranty liability, which is included as a component of accrued liabilities on the condensed consolidated balance sheets, are set forth in the table below (in thousands). The reserves below do not include reserves established as a result of the manufacturing process quality issue described below under the heading “Manufacturing Process Quality Reserve.” Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Warranty reserve, beginning of period $ 4,859 $ 1,306 $ 2,158 $ 763 Provisions made to warranty reserve during the period 3,483 2,334 9,456 4,120 Charges against warranty reserve during the period (4,923 ) (1,531 ) (8,195 ) (2,774 ) Warranty reserve, end of period $ 3,419 $ 2,109 $ 3,419 $ 2,109

SEGMENT INFORMATION AND GEOGR34

SEGMENT INFORMATION AND GEOGRAPHIC DATA (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Summary of Revenue by Geographic Region	Revenue by geographic region, based on ship-to destinations, was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 United States $ 11,333 $ 25,644 $ 47,561 $ 65,660 China 37,234 55,665 123,583 143,017 Germany 21,171 37,333 43,786 82,054 Thailand 15,975 5,255 32,694 14,251 Other 19,285 11,407 50,939 31,003 Total revenue $ 104,998 $ 135,304 $ 298,563 $ 335,985
Summary of Total Long-Lived Assets by Geographic Region	Total long-lived assets by geographic region consisted of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 United States $ 16,575 $ 14,026 China 1,275 2,235 Thailand 6,680 8,070 Other 560 793 Total long-lived assets $ 25,090 $ 25,124

CONCENTRATIONS OF RISK (Tables)

CONCENTRATIONS OF RISK (Tables)	9 Months Ended
	Sep. 30, 2017
Customer Concentration Risk
Concentration Risk [Line Items]
Summary of Concentrations of Risk	Customers with revenue equal to or greater than 10% of total revenue for the three and nine months ended September 30, 2017 and 2016 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 A 31 % 28 % 34 % 34 % B 16 % 35 % 15 % 28 % C 15 % * 11 % * D 13 % * * * * Less than 10% of revenue in the period indicated Customers that accounted for equal to or greater than 10% of accounts receivable at September 30, 2017 and December 31, 2016 were as follows: September 30, 2017 December 31, 2016 A 29 % 26 % B * 19 % C 24 % 15 % D 12 % * * Less than 10% of accounts receivable at the date indicated
Supplier Concentration Risk
Concentration Risk [Line Items]
Summary of Concentrations of Risk	For the three and nine months ended September 30, 2017 and 2016 , total purchases from each of the suppliers was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 W * * 25 % * X 20 % 42 % 22 % 43 % Y 47 % 27 % 32 % 20 % Z * 18 % 15 % 19 % * Less than 10% of total purchases in the period indicated

NATURE OF THE BUSINESS AND OP36

NATURE OF THE BUSINESS AND OPERATIONS (Details)	Oct. 13, 2016USD ($)$ / sharesshares	May 18, 2016USD ($)$ / sharesshares	Sep. 30, 2017USD ($)GBTB	Sep. 30, 2016USD ($)
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Optical interconnect modules transmission speed | TB			1
Aggregate proceeds from IPO			$ 0	$ 97,757,000
IPO
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Common stock, issued and sold (in shares) | shares		4,570,184
Additional shares sold by selling stockholders (in shares) | shares		604,816
Price per share (in USD per share) | $ / shares		$ 23
Aggregate proceeds from IPO		$ 97,800,000
Offering expenses		$ 4,300,000
Conversion of redeemable preferred stock into common stock (in shares) | shares		24,177,495
Stock offered through certain selling stockholders
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Proceeds from sale of shares		$ 0
Follow-on offering
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Common stock, issued and sold (in shares) | shares	1,210,302
Additional shares sold by selling stockholders (in shares) | shares	3,289,698
Price per share (in USD per share) | $ / shares	$ 100
Offering expenses	$ 1,200,000
Proceeds from sale of shares	116,800,000
Proceeds from sale of shares	$ 0
Minimum
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Optical interconnect modules transmission speed | GB			100
Maximum
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Optical interconnect modules transmission speed | GB			400
Maximum | Underwriters
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Additional shares sold by selling stockholders (in shares) | shares	675,000

FINANCIAL INSTRUMENTS - Schedul

FINANCIAL INSTRUMENTS - Schedule of Cash, Cash Equivalents and Short- and Long-term Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	$ 348,507	$ 310,433
Gross Unrealized Gains	42	2
Gross Unrealized Losses	(85)	(29)
Estimated Fair Value	348,464	310,406
Cash and Cash Equivalents	115,761	206,402	$ 122,914	$ 27,610
Marketable Securities	232,703	104,004
Corporate debt securities
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	135,292	46,339
Gross Unrealized Gains	27	2
Gross Unrealized Losses	(77)	(27)
Estimated Fair Value	135,242	46,314
Cash and Cash Equivalents	451	1,001
Marketable Securities	134,791	45,313
Cash
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	61,351	81,230
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	61,351	81,230
Cash and Cash Equivalents	61,351	81,230
Marketable Securities	0	0
Money market funds
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	17,461	118,174
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	17,461	118,174
Cash and Cash Equivalents	17,461	118,174
Marketable Securities	0	0
Repurchase agreements
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	25,000
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Estimated Fair Value	25,000
Cash and Cash Equivalents	25,000
Marketable Securities	0
U.S. treasury bonds
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	2,196	15,017
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	(2)
Estimated Fair Value	2,194	15,015
Cash and Cash Equivalents	0	0
Marketable Securities	2,194	15,015
Commercial paper
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	54,520	49,673
Gross Unrealized Gains	2	0
Gross Unrealized Losses	0	0
Estimated Fair Value	54,522	49,673
Cash and Cash Equivalents	10,498	5,997
Marketable Securities	44,024	$ 43,676
Certificates of deposit
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	25,999
Gross Unrealized Gains	8
Gross Unrealized Losses	(2)
Estimated Fair Value	26,005
Cash and Cash Equivalents	1,000
Marketable Securities	25,005
Asset-backed securities
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	26,688
Gross Unrealized Gains	5
Gross Unrealized Losses	(4)
Estimated Fair Value	26,689
Cash and Cash Equivalents	0
Marketable Securities	$ 26,689

FINANCIAL INSTRUMENTS - Proceed

FINANCIAL INSTRUMENTS - Proceeds from Sales and Maturities of Marketable Securities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Proceeds from the sales and maturities of marketable securities	$ 77,053	$ 177,353	$ 0
Realized gains	3	7
Realized losses	$ (1)	$ (1)

FINANCIAL INSTRUMENTS - Contrac

FINANCIAL INSTRUMENTS - Contractual Maturities of Short-term and Long-term Marketable Securities Held (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Due within one year, Amortized Cost Basis	$ 173,395	$ 104,031
Due within one year, Aggregate Fair Value	173,388	104,004
Due after 1 year through 2 years, Amortized Cost Basis	59,350	0
Due after 1 year through 2 years, Aggregate Fair Value	59,315	0
Amortized Cost Basis	232,745	104,031
Aggregate Fair Value	$ 232,703	$ 104,004

INVENTORY - Schedule of Invento

INVENTORY - Schedule of Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 27,554	$ 14,385
Work-in-process	1,476	3,235
Finished goods	20,953	14,061
Inventory	$ 49,983	$ 31,681

PROPERTY AND EQUIPMENT - Schedu

PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 49,981	$ 42,443
Less: Accumulated depreciation	(24,891)	(17,319)
Property and equipment, net	25,090	25,124
Engineering laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	36,909	31,096
Computer software
Property, Plant and Equipment [Line Items]
Total property and equipment	1,751	1,381
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	3,775	2,572
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	2,922	408
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	2,341	1,032
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 2,283	$ 5,954

PROPERTY AND EQUIPMENT - Narrat

PROPERTY AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 3,300	$ 2,700	$ 9,101	$ 6,536

ACCRUED LIABILITIES - Schedule

ACCRUED LIABILITIES - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Employee-related liabilities	$ 6,942		$ 6,235
Outsourced foundry services	95		1,811
Goods and services received not invoiced	11,838		9,024
Accrued income taxes	940		670
Accrued manufacturing related expenses	7,982		5,255
Warranty reserve	3,419	$ 4,859	2,158	$ 2,109	$ 1,306	$ 763
Other accrued liabilities	5,306		4,710
Accrued liabilities	$ 36,522		$ 29,863

FAIR VALUE MEASUREMENT - Summar

FAIR VALUE MEASUREMENT - Summary of Assets And Liabilities Measured at Fair Value on Recurring Basis (Details) - Recurring Basis - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 287,113	$ 229,176
Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	287,113	229,176
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Repurchase agreements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	25,000
Repurchase agreements | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
Repurchase agreements | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	25,000
Repurchase agreements | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
U.S. treasury bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,194	15,015
U.S. treasury bonds | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
U.S. treasury bonds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2,194	15,015
U.S. treasury bonds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	54,522	49,673
Commercial paper | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Commercial paper | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	54,522	49,673
Commercial paper | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	26,005
Certificates of deposit | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
Certificates of deposit | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	26,005
Certificates of deposit | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	26,689
Asset-backed securities | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
Asset-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	26,689
Asset-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	135,242	46,314
Corporate debt securities | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Corporate debt securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	135,242	46,314
Corporate debt securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	17,461	118,174
Money market funds | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Money market funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	17,461	118,174
Money market funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 0	$ 0

FAIR VALUE MEASUREMENT - Narrat

FAIR VALUE MEASUREMENT - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Transfers between fair value measurement levels	$ 0	$ 0

FAIR VALUE MEASUREMENT- Summary

FAIR VALUE MEASUREMENT- Summary of Changes in the Preferred Stock Warrant Liability Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Preferred stock warrant liability at beginning of period				$ 3,254
Change in fair value	$ 0	$ 0	$ 0	3,361
Reclassification of preferred stock warrant liability to additional paid-in capital upon conversion to common stock warrants				(6,615)
Preferred stock warrant liability at end of period		$ 0		$ 0

STOCK COMPENSATION PLANS - Clas

STOCK COMPENSATION PLANS - Classification of Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 6,420	$ 6,675	$ 17,162	$ 16,136
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	518	504	1,469	1,196
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	3,743	3,782	10,516	9,360
Sales, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 2,159	$ 2,389	$ 5,177	$ 5,580

STOCK COMPENSATION PLANS - Sche

STOCK COMPENSATION PLANS - Schedule of Stock-Based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 6,420	$ 6,675	$ 17,162	$ 16,136
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	331	283	882	434
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	648	623	1,969	1,391
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	29	29	87	76
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 5,412	$ 5,740	$ 14,224	$ 14,235

STOCK COMPENSATION PLANS - Stoc

STOCK COMPENSATION PLANS - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares
Number of Options, Abstract
Number of options outstanding at December 31, 2016 (in shares)	2,354
Number of options granted (in shares)	0
Number of options exercised (in shares)	(599)
Number of options cancelled (in shares)	(11)
Number of options outstanding at September 30, 2017 (in shares)	1,744	2,354
Number of options vested and expected to vest (in shares)	1,744	2,354
Number of options exercisable (in shares)	879	975
Weighted-Average Exercise Price, Abstract
Weighted-average exercise price outstanding at December 31, 2016 (in USD per share) | $ / shares	$ 7.10
Options exercised, Weighted-average exercise price (in USD per share) | $ / shares	3.95
Options cancelled, Weighted-average exercise price (in USD per share) | $ / shares	8.81
Weighted-average exercise price outstanding at September 30, 2017 (in USD per share) | $ / shares	8.17	$ 7.10
Options vested and expected to vest, Weighted-average exercise price (in USD per share) | $ / shares	8.17	7.10
Options exercisable, Weighted-average exercise price (in USD per share) | $ / shares	$ 4.63	$ 1.78
Weighted-Average Remaining Contract Term, Abstract
Options outstanding, Weighted-average remaining contractual term (in years)	6 years 10 months 24 days	7 years 4 months 24 days
Options vested and expected to vest, Weighted-average remaining contractual term (in years)	6 years 10 months 24 days	7 years 4 months 24 days
Options exercisable, Weighted-average remaining contractual term (in years)	6 years	6 years 1 month 6 days
Aggregate Intrinsic Value, Abstract
Options outstanding, Aggregate intrinsic value at December 31, 2016 | $	$ 129,288
Options exercised, Aggregate intrinsic value | $	30,051
Options outstanding, Aggregate intrinsic value at September 30, 2017 | $	69,095	$ 129,288
Options vested and expected to vest, Aggregate intrinsic value | $	69,095	129,288
Options exercisable, Aggregate intrinsic value | $	$ 37,626	$ 58,458

STOCK COMPENSATION PLANS - Narr

STOCK COMPENSATION PLANS - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted (in shares)				0
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost, stock options		$ 5,500,000		$ 5,500,000		$ 7,600,000
Weighted average recognition period				2 years 4 months 24 days		3 years 1 month 6 days
Weighted average grant date fair value (in USD per share)			$ 34.82		$ 10.97
Number of options granted (in shares)		0		0
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average recognition period				3 years 1 month 6 days		3 years 4 months 24 days
Restricted stock units granted (in shares)				998,000
Vested awards settled in cash				$ 0
Unrecognized stock-based compensation expense		$ 51,900,000		$ 51,900,000		$ 32,100,000
Restricted stock units | Employees and Executives | 2016 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted (in shares)				537,000
Awards vesting period				4 years
Performance-Based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period				4 years
Right to receive number of common stock upon achievement of vesting conditions				1
Stock price objective period				2 years
Performance-Based RSUs | Executive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted (in shares)	461,000			461,000
Performance-Based RSUs | Executive | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted (in shares)				461,000
Earned PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance objective period				2 years
Earned PRSUs | Vest on March 17, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of earned PRSUs				33.00%
Earned PRSUs | Vest on March 17, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of earned PRSUs				33.00%
Earned PRSUs | Vest on March 17, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of earned PRSUs				34.00%

STOCK COMPENSATION PLANS - Weig

STOCK COMPENSATION PLANS - Weighted-Average Assumptions Used to Estimate Fair Value (Details) - Performance-Based RSUs	9 Months Ended
	Sep. 30, 2017$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.30%
Expected dividend yield	0.00%
Expected volatility	58.30%
Expected term (in years)	1 year 9 months 18 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value of underlying shares (in USD per share)	$ 40.38
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value of underlying shares (in USD per share)	$ 55.02

STOCK COMPENSATION PLANS - Chan

STOCK COMPENSATION PLANS - Changes in Company Restricted Stock Units (Details) - Restricted stock units shares in Thousands	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Shares outstanding at December 31, 2016 (in shares) | shares	2,034
Granted (in shares) | shares	998
Vested (in shares) | shares	(603)
Cancelled (in shares) | shares	(8)
Shares outstanding at September 30, 2017 (in shares) | shares	2,421
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Shares outstanding, Weighted-average grant date fair value at December 31, 2016 (in USD per share) | $ / shares	$ 21.09
Granted, Weighted-average grant date fair value (in USD per share) | $ / shares	54.20
Vested, Weighted-average grant date fair value (in USD per share) | $ / shares	19.17
Cancelled, Weighted-average grant date fair value (in USD per share) | $ / shares	29.35
Shares outstanding, Weighted-average grant date fair value at September 30, 2017 (in USD per share) | $ / shares	$ 35.19

NET INCOME PER SHARE ATTRIBUT53

NET INCOME PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017
Earnings Per Share [Line Items]
Earnings allocated to participating securities		$ 0	$ 0	$ 0
Performance-Based RSUs | Executive
Earnings Per Share [Line Items]
Restricted stock units granted (in shares)	461,000			461,000

NET INCOME PER SHARE ATTRIBUT54

NET INCOME PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS - Computation of Basic and Diluted Net Income Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net income	$ 18,499	$ 34,888	$ 58,872	$ 67,083
Less: preferred stock accretion	0	0	0	(1,722)
Less: undistributed earnings attributable to participating securities	0	0	0	(23,959)
Net income attributable to common stockholders - basic	18,499	34,888	58,872	41,402
Net income attributable to common stockholders - diluted	$ 18,499	$ 34,888	$ 58,872	$ 41,402
Denominator:
Weighted-average shares used to compute net income per share attributable to common stockholders - basic (in shares)	39,259	35,922	38,754	21,195
Dilutive effect of stock options, unvested restricted stock and restricted stock units, preferred stock warrants, and employee stock purchase plan (in shares)	2,498	4,786	2,906	3,988
Weighted-average shares used to compute net income per share attributable to common stockholders - diluted (in shares)	41,757	40,708	41,660	25,183
Net income per share attributable to common stockholders
Basic (in USD per share)	$ 0.47	$ 0.97	$ 1.52	$ 1.95
Diluted (in USD per share)	$ 0.44	$ 0.86	$ 1.41	$ 1.64

NET INCOME PER SHARE ATTRIBUT55

NET INCOME PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS - Summary of Common Stock Equivalents Excluded from Computation of Diluted Net Income Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	0	0	0	245
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	90	17	90	30
Unvested restricted stock units and awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	545	21	424	16
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	48	0	0	0

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended
	May 31, 2017contract_manufacturerAC400_UnitCFP_Unit	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)AC400_UnitCFP_Unit	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Loss Contingencies [Line Items]
Operating leases rent expense		$ 1.2	$ 0.3		$ 3.9	$ 0.9
Minimum
Loss Contingencies [Line Items]
Standard warranty period on repair or replacement of defective products					12 months
Maximum
Loss Contingencies [Line Items]
Standard warranty period on repair or replacement of defective products					24 months
Contract manufacturer quality issue
Loss Contingencies [Line Items]
Number of contract manufacturers with quality issue | contract_manufacturer	1
Number of contract manufacturers | contract_manufacturer	3
Quality issue warranty accrual		1.1		$ 1.1	$ 1.1
Inventory reserves		5.5		$ 5.5	5.5
Contract manufacturer quality issue | AC400 Unit
Loss Contingencies [Line Items]
Defective units | AC400_Unit	1,300			1,900
Contract manufacturer quality issue | CFP Unit
Loss Contingencies [Line Items]
Defective units | CFP_Unit	5,100			7,000
Construction build-out | Massachusetts facility
Loss Contingencies [Line Items]
Commitment to additional construction		$ 0.9		$ 0.9	$ 0.9

COMMITMENTS AND CONTINGENCIES57

COMMITMENTS AND CONTINGENCIES - Future Annual Minimum Lease Payments (Details) $ in Thousands	Sep. 30, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remaining 2,017	$ 869
2,018	3,342
2,019	3,306
2,020	3,335
2,021	3,244
Thereafter	7,835
Total	$ 21,931

COMMITMENTS AND CONTINGENCIES58

COMMITMENTS AND CONTINGENCIES - Schedule of Changes in Product Warrant Liability (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Warranty reserve, beginning of period	$ 4,859	$ 1,306	$ 2,158	$ 763
Provisions made to warranty reserve during the period	3,483	2,334	9,456	4,120
Charges against warranty reserve during the period	(4,923)	(1,531)	(8,195)	(2,774)
Warranty reserve, end of period	$ 3,419	$ 2,109	$ 3,419	$ 2,109

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
(Benefit) provision for income taxes	$ (8,628)	$ 2,122	$ (24,560)	$ 5,918
Effective income tax rate	(87.40%)	5.70%	(71.60%)	8.10%
Uncertain tax positions	$ 4,600		$ 4,600		$ 3,100
Unrecognized tax benefits that, if recognized, would favorably impact effective tax rate	$ 2,500		$ 2,500		$ 1,500

SEGMENT INFORMATION AND GEOGR60

SEGMENT INFORMATION AND GEOGRAPHIC DATA - Narrative (Details)	9 Months Ended
	Sep. 30, 2017segment
Segment Reporting [Abstract]
Number of operating segments	1

SEGMENT INFORMATION AND GEOGR61

SEGMENT INFORMATION AND GEOGRAPHIC DATA - Summary of Revenue by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 104,998	$ 135,304	$ 298,563	$ 335,985
United States
Segment Reporting Information [Line Items]
Revenue	11,333	25,644	47,561	65,660
China
Segment Reporting Information [Line Items]
Revenue	37,234	55,665	123,583	143,017
Germany
Segment Reporting Information [Line Items]
Revenue	21,171	37,333	43,786	82,054
Thailand
Segment Reporting Information [Line Items]
Revenue	15,975	5,255	32,694	14,251
Other
Segment Reporting Information [Line Items]
Revenue	$ 19,285	$ 11,407	$ 50,939	$ 31,003

SEGMENT INFORMATION AND GEOGR62

SEGMENT INFORMATION AND GEOGRAPHIC DATA - Summary of Total Long-Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property and equipment, net	$ 25,090	$ 25,124
United States
Segment Reporting Information [Line Items]
Property and equipment, net	16,575	14,026
China
Segment Reporting Information [Line Items]
Property and equipment, net	1,275	2,235
Thailand
Segment Reporting Information [Line Items]
Property and equipment, net	6,680	8,070
Other
Segment Reporting Information [Line Items]
Property and equipment, net	$ 560	$ 793

CONCENTRATIONS OF RISK - Summar

CONCENTRATIONS OF RISK - Summary of Customer Concentration of Total Revenue (Details) - Customer Concentration Risk - Revenue	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	31.00%	28.00%	34.00%	34.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	16.00%	35.00%	15.00%	28.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	15.00%		11.00%
Customer D
Concentration Risk [Line Items]
Concentration risk, percentage	13.00%

CONCENTRATIONS OF RISK - Summ64

CONCENTRATIONS OF RISK - Summary of Customer Concentration of Accounts Receivable (Details) - Customer Concentration Risk - Accounts Receivable	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	29.00%	26.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage		19.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	24.00%	15.00%
Customer D
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%

CONCENTRATIONS OF RISK - Summ65

CONCENTRATIONS OF RISK - Summary of Supplier Concentration (Details) - Supplier Concentration Risk - Purchases	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Supplier W
Concentration Risk [Line Items]
Concentration risk, percentage			25.00%
Supplier X
Concentration Risk [Line Items]
Concentration risk, percentage	20.00%	42.00%	22.00%	43.00%
Supplier Y
Concentration Risk [Line Items]
Concentration risk, percentage	47.00%	27.00%	32.00%	20.00%
Supplier Z
Concentration Risk [Line Items]
Concentration risk, percentage		18.00%	15.00%	19.00%

CONCENTRATIONS OF RISK - Narrat

CONCENTRATIONS OF RISK - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Supplier Concentration Risk | Revenue | Research and development
Concentration Risk [Line Items]
Concentration risk, percentage	25.00%	16.00%	17.00%	17.00%

RELATED PARTIES - Narrative (De

RELATED PARTIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
ADI
Related Party Transaction [Line Items]
Purchase from related party	$ 1.4	$ 1.5	$ 3.5	$ 3.3
M/A-COM
Related Party Transaction [Line Items]
Purchase from related party	$ 0.2	$ 0.5	$ 0.7	$ 1.4