Acacia Communications (ACIA) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 27, 2018
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	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		40,550,197

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 100,656	$ 67,495
Marketable securities - short-term	202,759	211,933
Accounts receivable	56,399	86,602
Inventory	50,650	62,232
Prepaid expenses and other current assets	21,053	18,985
Total current assets	431,517	447,247
Marketable securities - long-term	71,363	85,182
Property and equipment, net	29,507	28,175
Deferred tax asset	51,670	41,901
Other assets	8,112	8,745
Total assets	592,169	611,250
Current liabilities:
Accounts payable	28,663	47,819
Accrued liabilities	33,230	37,234
Deferred revenue	336	573
Total current liabilities	62,229	85,626
Income taxes payable	19,205	21,034
Other long-term liabilities	4,808	2,540
Total liabilities	86,242	109,200
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000 shares authorized; none issued and outstanding at June 30, 2018 and December 31, 2017	0	0
Common stock, $0.0001 par value; 150,000 shares authorized; 40,517 and 39,606 shares issued at June 30, 2018 and December 31, 2017, respectively	4	4
Treasury stock, at cost; 24 shares and none at June 30, 2018 and December 31, 2017, respectively	(771)	0
Additional paid-in capital	341,908	324,944
Accumulated other comprehensive loss	(515)	(320)
Retained earnings	165,301	177,422
Total stockholders’ equity	505,927	502,050
Total liabilities and stockholders’ equity	$ 592,169	$ 611,250

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
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)	40,517,000	39,606,000
Treasury stock, at cost (in shares)	24,000	0

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenue	$ 65,003	$ 78,898	$ 137,944	$ 193,565
Cost of revenue	39,798	53,516	88,668	111,883
Gross profit	25,205	25,382	49,276	81,682
Operating expenses:
Research and development	24,340	22,734	48,785	40,462
Sales, general and administrative	12,984	9,368	27,272	18,059
Gain on disposal of property and equipment	0	(47)	0	(47)
Total operating expenses	37,324	32,055	76,057	58,474
(Loss) income from operations	(12,119)	(6,673)	(26,781)	23,208
Other income, net:
Interest income, net	1,491	827	2,845	1,272
Other expense, net	(191)	(1)	(262)	(39)
Total other income, net	1,300	826	2,583	1,233
(Loss) income before benefit from income taxes	(10,819)	(5,847)	(24,198)	24,441
Benefit from income taxes	(7,574)	(10,511)	(11,875)	(15,932)
Net (loss) income	$ (3,245)	$ 4,664	$ (12,323)	$ 40,373
(Loss) earnings per share:
Basic (in USD per share)	$ (0.08)	$ 0.12	$ (0.31)	$ 1.05
Diluted (in USD per share)	$ (0.08)	$ 0.11	$ (0.31)	$ 0.97
Weighted-average shares used to compute (loss) earnings per share:
Basic (in shares)	40,307	38,756	40,074	38,546
Diluted (in shares)	40,307	41,582	40,074	41,639

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (3,245)	$ 4,664	$ (12,323)	$ 40,373
Other comprehensive income (loss):
Changes in unrealized loss on marketable securities, net of income taxes of $(54), $33, $13 and $(2) for the three and six months ended June 30, 2018 and 2017, respectively	253	22	(150)	(14)
Comprehensive (loss) income	$ (2,992)	$ 4,686	$ (12,473)	$ 40,359

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Changes in unrealized loss on marketable securities, tax	$ (54)	$ 13	$ 33	$ (2)

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2016		37,998	0
Beginning balance at Dec. 31, 2016	$ 434,795	$ 4	$ 0	$ 295,893	$ (16)	$ 138,914
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (in shares)		51
Exercise of common stock options (in shares)		523
Exercise of common stock options	1,903			1,903
Vesting of restricted stock units (in shares)		457
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	10,742			10,742
Unrealized losses on marketable securities, net of tax	(14)				(14)
Net (loss) income	40,373					40,373
Ending balance (in shares) at Jun. 30, 2017		39,059	0
Ending balance at Jun. 30, 2017	488,978	$ 4	$ 0	309,717	(30)	179,287
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effect of adopted accounting standards (see Note 2)	157				(45)	202
Beginning balance (in shares) at Dec. 31, 2017		39,606	0
Beginning balance at Dec. 31, 2017	502,050	$ 4	$ 0	324,944	(320)	177,422
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock acquired (in shares)			24
Treasury stock acquired	$ (771)		$ (771)
Vesting of restricted common stock (in shares)		21
Exercise of common stock options (in shares)	348	348
Exercise of common stock options	$ 1,520			1,520
Vesting of restricted stock units (in shares)		485
Common stock issued under employee stock purchase plan (in shares)		57
Common stock issued under employee stock purchase plan	1,367			1,367
Stock-based compensation expense	14,077			14,077
Unrealized losses on marketable securities, net of tax	(150)				(150)
Net (loss) income	(12,323)					(12,323)
Ending balance (in shares) at Jun. 30, 2018		40,517	(24)
Ending balance at Jun. 30, 2018	$ 505,927	$ 4	$ (771)	$ 341,908	$ (515)	$ 165,301

CONDENSED CONSOLIDATED STATEME8

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Stockholders' Equity [Abstract]
Changes in unrealized loss on marketable securities, tax	$ (54)	$ 13	$ 33	$ (2)

CONDENSED CONSOLIDATED STATEME9

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (loss) income	$ (12,323)	$ 40,373
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation	6,634	5,841
Gain on disposal of property and equipment	0	(47)
Stock-based compensation	14,126	10,742
Deferred income taxes	(9,823)	(13,939)
Other non-cash (benefits) charges	(47)	158
Changes in operating assets and liabilities:
Accounts receivable	30,203	25,216
Inventory	11,582	(10,005)
Prepaid expenses and other current assets	(2,236)	(6,721)
Other assets	613	(4,560)
Accounts payable	(17,439)	(12,364)
Accrued liabilities	(4,053)	925
Deferred revenue	2,826	155
Income taxes payable	(1,829)	0
Other long-term liabilities	(420)	459
Net cash provided by operating activities	17,814	36,233
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(9,683)	(8,006)
Purchases of marketable securities	(142,614)	(233,246)
Sales and maturities of marketable securities	165,508	100,300
Deposits	20	(30)
Net cash provided by (used in) investing activities	13,231	(140,982)
CASH FLOWS FROM FINANCING ACTIVITIES:
Treasury stock acquired	(771)	0
Payment of public offering costs	0	(201)
Proceeds from the issuance of common stock under stock-based compensation plans	2,887	3,082
Net cash provided by financing activities	2,116	2,881
Net increase (decrease) in cash, cash equivalents and restricted cash	33,161	(101,868)
Cash, cash equivalents and restricted cash—Beginning of period	67,495	208,032
Cash, cash equivalents and restricted cash—End of period	100,656	106,164
Supplemental cash flow disclosures:
Cash paid for income taxes, net of refunds	659	833
Supplemental disclosure of non-cash investing and financing activities:
Capital expenditures incurred but not yet paid	$ 1,025	$ 140

NATURE OF THE BUSINESS AND OPER

NATURE OF THE BUSINESS AND OPERATIONS	6 Months Ended
	Jun. 30, 2018
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 optical interconnect products that transform communications networks, relied upon by cloud infrastructure operators and content and communication service providers, through improvements in performance and capacity and reductions in associated costs. The Company’s products include a family of low-power coherent digital signal processors and silicon photonic integrated circuits that it has 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 sampling its AC1200 module that will enable, across dual wavelengths, transmission capacity of 1.2 terabits (1,200 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.

BASIS OF PRESENTATION AND SUMMA

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2018
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, 2017 , which was filed with the SEC on February 22, 2018. 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, 2017 , 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 June 30, 2018 , its condensed consolidated statements of operations for the three and six months ended June 30, 2018 and 2017 , its condensed consolidated statements of comprehensive (loss) income for the three and six months ended June 30, 2018 and 2017 , its condensed consolidated statements of stockholders’ equity for the six months ended June 30, 2018 and 2017 , and its condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 . 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 the three and six months ended June 30, 2018 and 2017 are also unaudited. The results of operations for the three and six months ended June 30, 2018 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. Reclassifications Certain prior period amounts have been reclassified to conform to the current period presentation. Specifically, for the six months ended June 30, 2017 , the $0.3 million increase in deferred product costs has now been included within the increase in “Prepaid expenses and other current assets” on the condensed consolidated statement of cash flows. Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASC 606”) which supersedes the revenue recognition requirements in Accounting Standard Codification 605, Revenue Recognition (“ASC 605”) and affects any entity that enters into contracts with customers to transfer goods and services. On January 1, 2018, the Company adopted ASC 606 and all related amendments for all contracts not completed as of the adoption date using the modified retrospective method. The Company recognized the $0.2 million cumulative effect of initially applying ASC 606 as an adjustment to the opening balance of retained earnings. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. In accordance with ASC 606, the Company recognizes revenue under the core principle to depict the transfer of control to the Company’s customers in an amount reflecting the consideration the Company expects to be entitled. In order to achieve that core principle, the Company applies the following five step approach: (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract and (5) recognize revenue when a performance obligation is satisfied. Revenue for product sales is recognized at the point in time when control transfers to the Company’s customers, which is generally when products are shipped from the Company’s manufacturing facilities or when delivered to the customer’s named location. When the Company performs shipping and handling activities after the transfer of control to the customer (e.g., when control transfers prior to delivery), they are considered to be fulfillment activities, and accordingly, the costs are accrued for when the related revenue is recognized. Taxes collected from customers relating to product sales and remitted to governmental authorities are excluded from revenue. See Note 3 for further disclosures and detail regarding revenue. As the impact of ASC 606 is not material to the Company, there is no pro-forma disclosure presented as of and for the three and six months ended June 30, 2018 . The Company expects the impact of the adoption of the new standard to be immaterial to its results of operations on an ongoing basis. 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 were adopted by the Company in the first quarter of 2018. The amendments in ASU 2016-16 were applied using a modified retrospective approach. As the Company has not had any intra-entity transfers of assets in such period other than inventory, there has been no impact from the adoption of this standard. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows - Restricted Cash (“ASU 2016-18”) . The amendments in ASU 2016-18 require that the statement of cash flows explain the change in total cash, cash equivalents and restricted cash. ASU 2016-18 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted the amendments in ASU 2016-18 in the first quarter of 2018 using a retrospective transition method. Other than the revised statement of cash flows presentation of restricted cash in the prior period presented, which was immaterial, the adoption of ASU 2016-18 did not have a material impact on the Company’s condensed consolidated financial statements for the three and six months ended June 30, 2017 . There is no impact to the cash flow statement for the six months ended June 30, 2018 as there was no restricted cash balance as of the beginning or end of the period. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”). ASU 2018-02 allows an entity to reclassify stranded income tax effects resulting from the U.S. Tax Cuts and Jobs Act (the “Act”) from accumulated other comprehensive loss to retained earnings. The amendments in ASU 2018-02 are effective for fiscal years beginning after December 15, 2018, with early adoption permitted, including adoption in any interim period for which financial statements have not yet been issued. The Company adopted and applied the ASU 2018-02 amendments in the second quarter of 2018. The adoption of the ASU 2018-02 amendments resulted in a $0.1 million cumulative-effect adjustment as of April 1, 2018, the first day of the Company’s second quarter of fiscal year 2018, between accumulated other comprehensive loss and retained earnings for the amount of the stranded tax effects. Recently Issued Accounting Pronouncements 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 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 statement of operations, 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 plans to adopt this guidance on January 1, 2019, and expects the adoption will have a material impact on its condensed consolidated balance sheets based on the valuation of right-of-use assets and lease liabilities, previously described as operating leases, calculated as the present value of the Company’s forecasted future lease commitments. The Company is continuing to assess the overall impacts of the new standard, including the discount rate to be applied in these valuations and increased leasing disclosures, as well as policy and process changes to support the new standard.

REVENUE

REVENUE	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE The Company adopted ASC 606 effective January 1, 2018 using the modified retrospective method. The Company recognized the cumulative effect of initially applying ASC 606 as an adjustment to the opening balance of retained earnings. The comparative information is accounted for in accordance with the previous revenue guidance, ASC 605, and has not been restated. Revenue recognized prior to the effective date is accounted for in accordance with the accounting policies disclosed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 . The following are the policies the Company has applied beginning January 1, 2018. The Company generates all of its revenue from contracts with customers. The Company considers customer purchase orders, which in many cases are governed by master purchasing agreements, to be contracts with customers. The Company’s contracts with customers are generally for product only, and do not include other performance obligations such as services, extended warranties or other material rights. As part of its assessment of each contract, the Company evaluates certain factors including the customer’s ability to pay (or credit risk). For each contract, the Company considers the promise to transfer products, each of which is distinct, to be the identified performance obligations. In determining the transaction price, the price stated on the purchase order is typically fixed and represents the net consideration to which the Company expects to be entitled, and therefore there is no variable consideration. As the Company’s standard payment terms are less than one year, the Company has elected, as a practical expedient, to not assess whether a contract has a significant financing component. The Company allocates the transaction price to each distinct product based on its relative standalone selling price. The product price as specified on the purchase order is considered the standalone selling price as it is an observable source that depicts the price as if sold to a similar customer in similar circumstances. Revenue is recognized when control of the product is transferred to the customer (i.e., when the Company’s performance obligation is satisfied), which typically occurs upon shipment from the Company’s manufacturing site or delivery to the customer’s named location. In determining whether control has transferred, the Company considers if there is a present right to payment from the customer and when physical possession, legal title and risks and rewards of ownership have transferred to the customer. The Company also considered certain customer contracts that include acceptance clauses, but has concluded that delivery to the customer’s named location is the point at which the customer is able to direct the use of and obtain substantially all of the remaining benefits from the asset, and therefore the acceptance is considered a formality that does not impact the timing of revenue recognition. At times, the Company receives orders for products that may be delivered over multiple dates that may extend across reporting periods. The Company invoices for each delivery upon shipment and recognizes revenues for each distinct product delivered, assuming transfer of control has occurred. As scheduled delivery dates are within one year, the Company has elected to use the optional exemption whereby revenues allocated to future shipments of partially completed contracts are not disclosed. The Company generally provides an assurance warranty that its products will substantially conform to the agreed-upon specifications for 12 to 24 months from the date of shipment. The Company’s liability is limited to the cost of repair or replacement of the defective part. The Company does not consider activities related to such warranties to be a separate performance obligation. The terms and conditions of sale generally do not allow for refunds or product returns other than for warranty repairs. The Company has a limited number of customer contracts that provide for the performance of services or include multiple performance obligations. Once the Company determines the performance obligations, the Company determines the transaction price, which includes estimating the amount of variable consideration to be included in the transaction price, if any. The Company then allocates the transaction price to each performance obligation in the contract based on a relative stand-alone selling price method or using the variable consideration allocation exception if the required criteria are met. The corresponding revenues are recognized as the related performance obligations are satisfied. A receivable is recognized in the period the Company ships the product. Payment terms on invoiced amounts are based on contractual terms with each customer. In some cases, if control of the product has not yet transferred to the customer or the timing of the payments made by the customer precedes the Company’s fulfillment of the performance obligation, the Company recognizes a contract liability that is classified as “deferred revenue.” The opening and closing balances of the Company’s deferred revenue and accounts receivable are as follows (in thousands): Balance at Beginning of Period (1/1/18) (Decrease) / Increase Balance at End of Period Six Months Ended June 30, 2018 Accounts Receivable $ 86,602 (30,203 ) $ 56,399 Deferred Revenue (Current) $ 197 139 $ 336 Deferred Revenue (Non-current) $ 254 2,688 $ 2,942 The amounts of revenue recognized in the period that were included in the opening deferred revenue balance was immaterial for the three and six months ended June 30, 2018 . The increase in current and non-current deferred revenue is related to billings to, or advance payments from, customers for which the Company has not yet fulfilled its performance obligations. Deferred revenue not expected to be recognized within the Company’s operating cycle of one year is presented as a component of “Other long-term liabilities” on the condensed consolidated balance sheet. The Company has concluded that none of the costs it has incurred to obtain and fulfill its ASC 606 contracts meet the capitalization criteria, and as such, there are no costs deferred and recognized as assets on the condensed consolidated balance sheet. Disaggregation of Revenue The following table provides information about disaggregated revenue based on the geographic region of the Company’s customers’ ship-to destinations, which in certain instances may be the location of a contract manufacturer rather than the Company’s end customer. Further disaggregation of revenue by geographic country can be found in Note 13. Three Months Ended As a % of Six Months Ended As a % of June 30, 2018 Total Revenue June 30, 2018 Total Revenue (dollars in thousands) Americas $ 24,012 37 % $ 33,738 24 % EMEA 20,255 31 % 47,899 35 % APAC 20,736 32 % 56,307 41 % Total revenue $ 65,003 100 % $ 137,944 100 %

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 Gross Unrealized Losses Amortized Cost Gains Less than One Year Greater than One Year Estimated Fair Value Cash and Cash Equivalents Marketable Securities Cash $ 73,507 $ — $ — $ — $ 73,507 $ 73,507 $ — Money market funds 20,180 — — — 20,180 20,180 — U.S. treasury bonds 26,509 — (72 ) — 26,437 — 26,437 Commercial paper 44,011 1 (13 ) — 43,999 6,969 37,030 Certificates of deposit 48,418 18 (44 ) — 48,392 — 48,392 Asset-backed securities 38,708 1 (112 ) — 38,597 — 38,597 Corporate debt securities 124,077 9 (416 ) (4 ) 123,666 — 123,666 Total $ 375,410 $ 29 $ (657 ) $ (4 ) $ 374,778 $ 100,656 $ 274,122 December 31, 2017 Gross Unrealized Estimated Cash and Cash Marketable Amortized Cost Gains Losses (1) Fair Value Equivalents Securities Cash $ 43,223 $ — $ — $ 43,223 $ 43,223 $ — Money market funds 11,070 — — 11,070 11,070 — Repurchase agreements 12,500 — — 12,500 12,500 — U.S. treasury bonds 26,316 — (80 ) 26,236 — 26,236 Commercial paper 60,623 — (9 ) 60,614 — 60,614 Certificates of deposit 34,993 6 (33 ) 34,966 — 34,966 Asset-backed securities 33,374 1 (53 ) 33,322 702 32,620 Corporate debt securities 142,960 9 (290 ) 142,679 — 142,679 Total $ 365,059 $ 16 $ (465 ) $ 364,610 $ 67,495 $ 297,115 (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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Proceeds from the sales and maturities of marketable securities $ 77,678 $ 61,400 $ 165,508 $ 100,300 Realized gains $ 1 $ 3 $ 5 $ 4 Realized losses $ (30 ) $ — $ (32 ) $ — The contractual maturities of short-term and long-term marketable securities held at June 30, 2018 and December 31, 2017 are as follows (in thousands): June 30, 2018 December 31, 2017 Amortized Cost Basis Aggregate Fair Value Amortized Cost Basis Aggregate Fair Value Due within one year $ 203,190 $ 202,759 $ 212,137 $ 211,933 Due after one year through three years 71,564 71,363 85,426 85,182 Total $ 274,754 $ 274,122 $ 297,563 $ 297,115 At June 30, 2018 , 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	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
INVENTORY	INVENTORY Inventory consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Raw materials $ 36,033 $ 32,599 Work-in-process 388 965 Finished goods 14,229 28,668 Inventory $ 50,650 $ 62,232 On April 15, 2018, the U.S. Department of Commerce imposed a seven-year denial of export privileges that prohibited sales to ZTE Kangxun Telecom Co. Ltd. and certain of its affiliates, together ZTE, the Company’s largest customer (the “ZTE Ban”). As a result, the Company recorded inventory write-offs of $3.9 million in the first quarter of 2018 related to finished goods inventory that had either been designed specifically for ZTE, or had been intended for consumption by ZTE and had become excess inventory due to the suspension of sales to ZTE. On June 8, 2018, ZTE and the U.S. Department of Commerce reached a new settlement, pursuant to which the ZTE Ban was terminated and ZTE was removed from the Denied Persons List effective July 13, 2018.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT Property and equipment consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Engineering laboratory equipment $ 46,851 $ 39,433 Computer software 2,782 2,281 Computer equipment 5,025 4,380 Furniture and fixtures 3,219 3,041 Leasehold improvements 3,547 2,282 Construction in progress 2,499 4,591 Total property and equipment 63,923 56,008 Less: Accumulated depreciation (34,416 ) (27,833 ) Property and equipment, net $ 29,507 $ 28,175 Depreciation expense was $3.4 million and $3.0 million for the three months ended June 30, 2018 and 2017 , respectively, and $6.6 million and $5.8 million for the six months ended June 30, 2018 and 2017 , respectively.

ACCRUED LIABILITIES

ACCRUED LIABILITIES	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
ACCRUED LIABILITIES	ACCRUED LIABILITIES Accrued liabilities consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Employee-related liabilities $ 6,800 $ 5,233 Goods and services received not invoiced 6,285 12,827 Accrued manufacturing related expenses 3,951 4,007 Warranty reserve 7,077 8,306 Other accrued liabilities 9,117 6,861 Accrued liabilities $ 33,230 $ 37,234 Certain prior period amounts have been reclassified to conform to the current period presentation. Specifically, as of December 31, 2017, $0.1 million of “Outsourced foundry services” has now been reclassified to be presented within “Other accrued liabilities” in conformity with the current period presentation. Due to the ZTE Ban discussed in Note 5, the Company had $2.0 million of accrued manufacturing reserves as of June 30, 2018 related to estimated non-cancellable commitments to purchase inventory that was either designed specifically for ZTE, or was intended for consumption by ZTE and had become excess inventory due to the suspension of sales to ZTE. The Company is continuing to evaluate these estimates as a result of termination of the ZTE Ban effective July 13, 2018.

FAIR VALUE MEASUREMENT

FAIR VALUE MEASUREMENT	6 Months Ended
	Jun. 30, 2018
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 an original maturity of three months or less to be cash equivalents. The Company’s investments in money market funds, repurchase agreements, U.S. government agency debt securities, commercial paper, certificates of deposit, asset-backed securities and corporate 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 June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 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 $ — $ 20,180 $ — $ 20,180 U.S. treasury bonds — 26,437 — 26,437 Commercial paper — 43,999 — 43,999 Certificates of deposit — 48,392 — 48,392 Asset-backed securities — 38,597 — 38,597 Corporate debt securities — 123,666 — 123,666 Total $ — $ 301,271 $ — $ 301,271 December 31, 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 $ — $ 11,070 $ — $ 11,070 Repurchase agreements — 12,500 — 12,500 U.S. treasury bonds — 26,236 — 26,236 Commercial paper — 60,614 — 60,614 Certificates of deposit — 34,966 — 34,966 Asset-backed securities — 33,322 — 33,322 Corporate debt securities — 142,679 — 142,679 Total $ — $ 321,387 $ — $ 321,387 There were no transfers between fair value measurement levels during the three and six months ended June 30, 2018 or 2017 . For certain other financial instruments, including accounts receivable, accounts payable and other current liabilities, the carrying amounts approximate their fair value due to the relatively short maturity of these balances.

STOCK COMPENSATION PLANS

STOCK COMPENSATION PLANS	6 Months Ended
	Jun. 30, 2018
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 statements of operations for the three and six months ended June 30, 2018 and 2017 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cost of revenue $ 572 $ 511 $ 1,093 $ 953 Research and development 4,467 3,779 8,255 6,771 Sales, general and administrative 2,549 1,820 4,778 3,018 Total stock-based compensation $ 7,588 $ 6,110 $ 14,126 $ 10,742 The following table summarizes stock-based compensation expense by award type for the three and six months ended June 30, 2018 and 2017 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Stock options $ 588 $ 655 $ 1,189 $ 1,321 Restricted stock units 6,690 5,126 12,285 8,812 Employee stock purchase plan 285 300 583 551 Other awards 25 29 69 58 Total stock-based compensation $ 7,588 $ 6,110 $ 14,126 $ 10,742 Stock Options A summary of stock option activity under the Company’s equity incentive plans for the six months ended June 30, 2018 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, 2017 1,634 $ 8.34 6.6 $ 47,356 Granted 10 $ 28.77 Exercised (348 ) $ 4.37 $ 11,103 Cancelled (31 ) $ 11.47 Outstanding at June 30, 2018 1,265 $ 9.52 6.2 $ 33,915 Vested and expected to vest at: June 30, 2018 1,265 $ 9.52 6.2 $ 33,915 December 31, 2017 1,634 $ 8.34 6.6 $ 47,356 Exercisable at: June 30, 2018 785 $ 6.65 5.6 $ 22,953 December 31, 2017 907 $ 5.28 5.9 $ 28,634 As of June 30, 2018 and December 31, 2017 , there was $3.6 million and $4.8 million , respectively, of unrecognized compensation cost related to unvested common stock options which is expected to be recognized over weighted-average periods of 1.8 years and 2.2 years, respectively. The weighted-average grant date fair value of stock options granted during the three and six months ended June 30, 2018 was $15.58 . No stock option awards were issued by the Company during the three or six months ended June 30, 2017 . Restricted Stock Units During the six months ended June 30, 2018 , the Company granted approximately 613,000 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 six months ended June 30, 2018 , the Company granted awards covering up to a maximum of 90,808 performance-based RSUs to executive officers that include a market 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 PRSUs are subject to performance-based vesting. The number of PRSUs that vest is measured based on the level of achievement of a performance objective over a three -year period (the “Performance Period”) running from January 1, 2018 through December 31, 2020, as determined and certified by the Compensation Committee of the Board of Directors following the end of the Performance Period. The level of achievement will be determined based on the Company’s percentile achievement of relative total shareholder returns against an external comparator group during the Performance Period (the “Relative TSR Objective”). Vesting of the PRSUs is also subject to the applicable officer’s continued provision of services to the Company through the vesting date, except in the case of death or disability where vesting will be pro-rated for time worked during the Performance Period. No PRSUs will vest unless a threshold level of achievement of the Relative TSR Objective is achieved. 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 2.3% Expected dividend yield None Expected volatility 51.4% Expected term (in years) 2.9 Grant date fair value of underlying shares $39.02 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 six months ended June 30, 2018 is as follows: RSUs (in thousands) Weighted-Average Grant Date Fair Value Outstanding at December 31, 2017 2,288 $ 36.08 Granted 704 $ 41.51 Vested (485 ) $ 29.29 Cancelled (12 ) $ 26.76 Outstanding at June 30, 2018 2,495 $ 38.98 The granted amount includes the 90,808 PRSUs which is the maximum number that were granted to executives during the six months ended June 30, 2018 . As of June 30, 2018 and December 31, 2017 , there was $61.9 million and $47.8 million , respectively, of total unrecognized compensation cost related to unvested RSUs which is expected to be recognized over weighted-average periods of 2.8 years and 2.9 years, respectively.

NET (LOSS) INCOME PER SHARE

NET (LOSS) INCOME PER SHARE	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
NET (LOSS) INCOME PER SHARE	NET (LOSS) INCOME PER SHARE The following table sets forth the computation of the Company’s basic and diluted net (loss) income per share (in thousands, except per share amounts): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Numerator: Net (loss) income $ (3,245 ) $ 4,664 $ (12,323 ) $ 40,373 Denominator: Weighted-average shares used to compute net (loss) income per share - basic 40,307 38,756 40,074 38,546 Dilutive effect of stock options, unvested restricted stock and restricted stock units and employee stock purchase plan — 2,826 — 3,093 Weighted-average shares used to compute net (loss) income per share - diluted 40,307 41,582 40,074 41,639 Net (loss) income per share Basic $ (0.08 ) $ 0.12 $ (0.31 ) $ 1.05 Diluted $ (0.08 ) $ 0.11 $ (0.31 ) $ 0.97 The following common stock equivalents (in thousands) were excluded from the computation of diluted net (loss) income per share for the periods presented because including them would have been antidilutive: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Options to purchase common stock 1,030 90 1,126 90 Unvested restricted stock units and awards 1,699 562 1,665 381 Employee stock purchase plan 72 — 72 — As discussed further in Note 9, in February 2018, the Company granted a maximum of 90,808 PRSUs to executives that include a market condition and service conditions. As no shares would have been contingently issuable based on average market prices through June 30, 2018 , none have been included in the antidilutive table above.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2018
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 January 2022, with respect to the New Jersey facility. The Company also leases office space in various locations with expiration dates between 2018 and 2021 . 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 for the three months ended June 30, 2018 and 2017 , and $2.4 million and $2.7 million for the six months ended June 30, 2018 and 2017 , respectively. Future minimum lease payments due under these non-cancelable lease agreements as of June 30, 2018 , are as follows (in thousands): Amounts Remaining 2018 $ 1,687 2019 3,423 2020 3,452 2021 3,294 2022 2,410 Thereafter 5,546 Total $ 19,812 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. In May 2017, the Company announced a quality issue at one of its three contract manufacturers (the “Quality Issue”) that affected a portion of the units manufactured by the contract manufacturer over an approximate four month period, which is estimated at approximately 1,300 AC400 units and 5,100 CFP units under warranty. Based on the ongoing 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 associated with this Quality Issue. These costs are estimated based on the results of testing performed to date, which is ongoing, in addition to yield, fall-out rates and component part recovery cost estimates based on the Company’s historical experience. The Company’s estimates of the Quality Issue costs are subject to further change as final testing is performed. Changes in the Company’s 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): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Warranty reserve, beginning of period $ 7,418 $ 2,113 $ 8,306 $ 2,158 Provisions made to warranty reserve during the period 2,561 4,771 6,024 5,971 Charges against warranty reserve during the period (2,902 ) (2,025 ) (7,253 ) (3,270 ) Warranty reserve, end of period $ 7,077 $ 4,859 $ 7,077 $ 4,859 Legal Contingencies On January 21, 2016, ViaSat, Inc. filed a lawsuit in California state court, later removed to the U.S. District Court for the Southern District of California, 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 lawsuit 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. Based on the information available to the Company today, the Company currently believes that this lawsuit will not have a material adverse effect on the Company’s business or its consolidated financial position, results of operations or cash flows. On July 28, 2017, the Company filed a lawsuit in the Commonwealth of Massachusetts Superior Court - Business Litigation Session against ViaSat asserting commercial disparagement, libel, slander of title, unfair competition, intentional interference with advantageous relations and intentional interference with contractual relations. On April 5, 2018, ViaSat responded to the Company’s action and alleged counterclaims including, among other things, breach of contract, breach of the implied covenant of good faith and fair dealing, misappropriation of trade secrets, and unfair competition. The Company is still assessing the potential impact of this lawsuit. Both the California and Massachusetts lawsuits with ViaSat are still pending, and discovery is closed in the California action filed by ViaSat and ongoing in the Massachusetts action filed by the Company. 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 U.S. 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 follow-on 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. On November 7, 2017, the court consolidated these four securities class actions (under docket number 1:17-cv-11504). On November 9, 2017, the court appointed lead plaintiffs for the consolidated action. Lead plaintiffs filed a consolidated amended class action complaint on January 8, 2018. The amended complaint makes allegations similar to those in the original four complaints, against the same defendants, and alleges that some or all of the defendants violated Sections 11, 12(a)(2) and/or 15 of the Securities Act of 1933 and Sections 10(b) and/or 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder. All defendants filed motions to dismiss the consolidated amended complaint on February 9, 2018. The court held a hearing on the motions to dismiss on March 29, 2018, afforded the plaintiffs an additional 30 days to file a motion for leave to file a further amended complaint, and took the motions to dismiss under advisement. On April 30, 2018, plaintiffs filed a motion for leave to amend the complaint. On June 15, 2018, the court granted defendants’ motions to dismiss and denied plaintiffs leave to file an amended complaint. On June 25, 2018, the court entered judgment and dismissed the case against all the defendants. No notice of appeal has been filed. In November and December 2017, three purported shareholder derivative lawsuits were filed in the United States District Court for the District of Massachusetts against certain of the Company’s directors and executive officers (Murugesan Shanmugaraj, John Gavin, Francis Murphy, Eric Swanson, Peter Chung, Benny Mikkelsen, Stan Reiss, John Ritchie, Vincent Roche, Mehrdad Givehchi, Bhupendra Shah and Christian Rasmussen) and the Company as a nominal defendant. A fourth purported shareholder derivative lawsuit was filed against the same defendants on March 13, 2018. The complaints are captioned Colgan v. Shanmugaraj et al. , Case No. 1:17-cv-12350 (D. Mass.), filed November 29, 2017; Wong v. Shanmugaraj et al. , Case No. 1:17-cv-12550 (D. Mass.), filed December 22, 2017; Dennis v. Shanmugaraj et al. , Case No. 1:17-cv-12571 (D. Mass.), filed December 28, 2017; and Farah-Franco et al. v. Shanmugaraj et al. , Case No. 1:18-cv-10465 (D. Mass), filed March 13, 2018. The court has consolidated these complaints with the class actions (under docket number 1:17-cv-11504). The court appointed lead plaintiffs for the consolidated derivative actions on April 20, 2018. On May 1, 2018, plaintiff Dennis voluntarily dismissed his case without prejudice. Lead plaintiffs filed a consolidated amended derivative complaint on May 30, 2018. The amended derivative complaint generally alleges that the individual defendants breached fiduciary duties owed to the Company by making or causing the Company to make 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, and by selling stock in Acacia with knowledge of these allegedly false and/or misleading statements. The complaint also alleges that certain individual defendants caused the Company to issue an allegedly false and/or misleading proxy statement on or about April 6, 2017 regarding, among other matters, the reelection of certain directors. The complaint purports to assert derivative claims for violation of Section 11 of the Securities Act of 1933; Sections 10(b), 14(a), and 29(b) of the Securities Exchange Act of 1934, as well as Rule 10b-5 promulgated thereunder; breach of fiduciary duty; insider trading; waste of corporate assets; and unjust enrichment. The complaint seeks to recover on behalf of the Company for any liability it incurs as a result of the individual defendants’ alleged misconduct. The complaint also seeks declaratory, equitable and monetary relief, restitution, and attorneys’ fees and costs. On April 9, 2018, a purported shareholder filed a complaint against the Company in the Court of Chancery of the State of Delaware seeking to inspect certain of the Company’s books and records pursuant to 8 Del. C. §220 (“Section 220”). The complaint is captioned Silberberg v. Acacia Communications, Inc. , Case No. 2018-0262-TMR (Del. Ch.). The Company filed its answer on April 27, 2018. The plaintiff filed a motion for judgment on the pleadings on May 1, 2018. The Company filed its cross-motion for judgment on the pleadings and opposition on May 11, 2018. The plaintiff replied on May 16, 2018. The Court held a telephonic hearing on these motions on May 29, 2018. On June 1, 2018, the Chancery Court granted the plaintiff’s motion and entered judgment for the plaintiff, and the Company thereafter produced documents to the shareholder pursuant to his Section 220 demand. On July 19, 2018, the parties reached an agreement in principle to settle the above-referenced derivative litigation and Section 220 litigation. The settlement involves certain corporate governance changes. The plaintiffs will seek an award of attorneys’ fees. The settlement is subject to negotiation of final documentation and court approval. There can be no assurance that the settlement will be approved by the court. The Company intends to continue to engage in a vigorous defense of the litigation 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, 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 its 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 on its 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 six months ended June 30, 2018 and 2017 , 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 June 30, 2018 and December 31, 2017 , no amounts have been accrued related to such indemnification provisions.

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Act was enacted on December 22, 2017 and, among other changes, this legislation: (1) reduced the U.S. federal corporate tax rate from 35% to 21%; (2) required companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax-deferred; (3) created new taxes on certain foreign sourced earnings; (4) provided a general elimination of U.S. federal income taxes on dividends from foreign subsidiaries; (5) included a new provision designed to currently tax certain global intangible low-taxed income (“GILTI”) of controlled foreign corporations, which allows for the possibility of using foreign tax credits (“FTCs”) and a deduction of up to 50 percent to reduce this income tax liability (subject to some limitations); (6) provided limitations on the use of FTCs to reduce the U.S. income tax liability from GILTI; and (7) provided limitations on net operating losses generated in the taxable years beginning after December 31, 2017 to 80 percent of taxable income. Accounting Standard Codification (“ASC”) 740 requires filers to record the effect of tax law changes in the period enacted. However, the SEC issued Staff Accounting Bulletin No. 118 (“SAB 118”) that permits filers to record provisional amounts during a measurement period ending no later than one year from the date of the Act’s enactment. As of June 30, 2018 , the Company has not completed the accounting for the tax effects of enactment of this legislation; however, the Company has made a reasonable estimate of the effects on its existing deferred tax balances, the one-time transition tax and provisional state taxes on future repatriations. For the items for which the Company was able to determine a reasonable estimate, the Company recognized a provisional amount of $31.4 million under SAB 118 as a component of income tax expense in the year ended December 31, 2017 . 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. As a result of the “deemed distributions” under the Act, the impact of GILTI on the Company’s future foreign earnings and lack of certain foreign governments’ withholding tax imposed on dividends, the Company no longer takes the position that its foreign earnings are permanently reinvested except for limited cases where foreign earnings are required to meet working capital needs. The Company’s tax provision for interim periods has historically been 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. In the six months ended June 30, 2018 , the Company’s tax benefit was limited and was calculated based on its year-to-date results. The Company’s quarterly tax (benefit) 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 June 30, 2018 , the Company recorded a benefit from income taxes of $7.6 million as compared to a benefit from income taxes of $10.5 million for the three months ended June 30, 2017 , resulting in an effective tax rate of 70.0% and 179.8% for the three months ended June 30, 2018 and 2017 , respectively. For the six months ended June 30, 2018 , the Company recorded a benefit from income taxes of $11.9 million as compared to a benefit from income taxes of $15.9 million for the six months ended June 30, 2017 , resulting in an effective tax rate of 49.1% and (65.2)% for the six months ended June 30, 2018 and 2017 , respectively. The benefit from income taxes recorded in the three and six months ended June 30, 2018 is primarily a result of the Company’s pre-tax loss position, the recognition of excess tax benefits from the taxable compensation on share-based awards recognized in the three and six months ended June 30, 2018 and federal and state research and development credits. The benefit from income taxes recorded in the three and six months ended June 30, 2017 was primarily a result of the recognition of excess tax benefits from the taxable compensation on share-based awards recognized in the three and six months ended June 30, 2017 and the favorable effect of foreign statutory tax rates applicable to income earned outside the United States under the Company’s corporate structure. The Company’s historical (benefit) provision for income taxes is not necessarily reflective of its future results of operations. As of June 30, 2018 and December 31, 2017 , the Company identified $4.7 million and $4.5 million , respectively, of gross uncertain tax positions. Included in those balances as of June 30, 2018 and December 31, 2017 are $1.9 million and $2.3 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 six months ended June 30, 2018 and 2017 , the amounts recorded related to the accrual of interest and penalties were immaterial in each period. On July 24, 2018, the Ninth Circuit Court of Appeals issued an opinion in Altera Corp. v. Commissioner requiring related parties in an intercompany cost-sharing arrangement to share expenses related to share-based compensation. This opinion reversed the prior decision of the United States Tax Court. The Company is currently evaluating the opinion and its application to the Company’s facts and circumstances which could adversely affect the Company’s tax obligations and effective tax rate for the third quarter.

SEGMENT INFORMATION AND GEOGRAP

SEGMENT INFORMATION AND GEOGRAPHIC DATA	6 Months Ended
	Jun. 30, 2018
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, which in certain instances may be the location of a contract manufacturer rather than the Company’s end customer, was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 United States $ 23,159 $ 23,814 $ 32,586 $ 36,227 China 12,909 29,367 34,993 86,349 Germany 10,086 9,649 29,832 22,615 Thailand 4,853 5,115 11,972 16,719 Other 13,996 10,953 28,561 31,655 Total revenue $ 65,003 $ 78,898 $ 137,944 $ 193,565 Total long-lived assets by geographic region consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 United States $ 19,969 $ 19,065 China 1,740 1,165 Thailand 5,409 7,065 Other 2,389 880 Total long-lived assets $ 29,507 $ 28,175

CONCENTRATIONS OF RISK

CONCENTRATIONS OF RISK	6 Months Ended
	Jun. 30, 2018
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 six months ended June 30, 2018 and 2017 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 A (1) * 28 % 14 % 36 % B 18 % 19 % 18 % 14 % C 14 % 15 % 17 % * D 12 % * * * * Less than 10% of revenue in the period indicated (1) Customer A was subject to U.S. Department of Commerce restrictions that prevented sales to this customer from April 15, 2018 through July 13, 2018. Customers that accounted for equal to or greater than 10% of accounts receivable at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 A (1) * 15 % B 14 % 10 % C 16 % 19 % * Less than 10% of accounts receivable at the date indicated (1) Customer A was subject to U.S. Department of Commerce restrictions that prevented sales to this customer from April 15, 2018 through July 13, 2018. 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 six months ended June 30, 2018 and 2017 , total purchases from each of the suppliers were as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 W * 11 % * 30 % X 12 % 20 % 15 % 23 % Y 47 % * 44 % 28 % Z * 12 % * 17 % * Less than 10% of total purchases in the period indicated The Company also outsources certain engineering projects to vendors located throughout the world. Total research and development costs incurred with Vendor A were less than 10% during the three and six months ended June 30, 2018 , and were 21% and 12% during the three and six months ended June 30, 2017 , respectively.

RELATED PARTIES

RELATED PARTIES	6 Months Ended
	Jun. 30, 2018
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. Based on shipments, the Company’s contract manufacturers made purchases from ADI of approximately $0.7 million and $1.0 million during the three months ended June 30, 2018 and 2017 , respectively, and $1.4 million and $2.2 million during the six months ended June 30, 2018 and 2017 , respectively. In February 2018, the Company entered into a product development agreement with ADI related to the development of integrated circuits for $2.0 million , of which no costs were incurred during the three months ended June 30, 2018 and $0.5 million of costs were incurred during the six months ended June 30, 2018 . One of the members of the Company’s Board of Directors, Peter Y. Chung, is also a member of the board of directors of M/A-COM Technology Solutions, Inc. (“MACOM”). The Company, through its contract manufacturers, periodically purchases supplies from MACOM. These purchased supplies are used as content in certain of the Company’s manufactured products. Based on shipments, the Company’s contract manufacturers made no purchases from MACOM during the three months ended June 30, 2018 and $0.3 million of purchases from MACOM during the six months ended June 30, 2018 . The amount of purchases made by the Company from MACOM were immaterial in the three and six months ended June 30, 2017 .

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS ZTE On June 8, 2018, ZTE and the U.S. Department of Commerce reached a new settlement, pursuant to which the ZTE Ban was terminated and ZTE was removed from the Denied Persons List effective July 13, 2018. The Company is cautiously optimistic that the termination of the ZTE Ban could have a favorable impact on its revenue in future periods. The Company has slowly started shipments to ZTE following the July 13, 2018 termination of the ZTE Ban and anticipates that shipments will increase during the third quarter as ZTE continues to ramp production. The Company continues to engage with ZTE to assess future demand for the Company’s products.

BASIS OF PRESENTATION AND SUM26

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2018
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.
Reclassifications	Reclassifications Certain prior period amounts have been reclassified to conform to the current period presentation.
Recently Adopted and Recently Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASC 606”) which supersedes the revenue recognition requirements in Accounting Standard Codification 605, Revenue Recognition (“ASC 605”) and affects any entity that enters into contracts with customers to transfer goods and services. On January 1, 2018, the Company adopted ASC 606 and all related amendments for all contracts not completed as of the adoption date using the modified retrospective method. The Company recognized the $0.2 million cumulative effect of initially applying ASC 606 as an adjustment to the opening balance of retained earnings. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. In accordance with ASC 606, the Company recognizes revenue under the core principle to depict the transfer of control to the Company’s customers in an amount reflecting the consideration the Company expects to be entitled. In order to achieve that core principle, the Company applies the following five step approach: (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract and (5) recognize revenue when a performance obligation is satisfied. Revenue for product sales is recognized at the point in time when control transfers to the Company’s customers, which is generally when products are shipped from the Company’s manufacturing facilities or when delivered to the customer’s named location. When the Company performs shipping and handling activities after the transfer of control to the customer (e.g., when control transfers prior to delivery), they are considered to be fulfillment activities, and accordingly, the costs are accrued for when the related revenue is recognized. Taxes collected from customers relating to product sales and remitted to governmental authorities are excluded from revenue. See Note 3 for further disclosures and detail regarding revenue. As the impact of ASC 606 is not material to the Company, there is no pro-forma disclosure presented as of and for the three and six months ended June 30, 2018 . The Company expects the impact of the adoption of the new standard to be immaterial to its results of operations on an ongoing basis. 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 were adopted by the Company in the first quarter of 2018. The amendments in ASU 2016-16 were applied using a modified retrospective approach. As the Company has not had any intra-entity transfers of assets in such period other than inventory, there has been no impact from the adoption of this standard. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows - Restricted Cash (“ASU 2016-18”) . The amendments in ASU 2016-18 require that the statement of cash flows explain the change in total cash, cash equivalents and restricted cash. ASU 2016-18 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted the amendments in ASU 2016-18 in the first quarter of 2018 using a retrospective transition method. Other than the revised statement of cash flows presentation of restricted cash in the prior period presented, which was immaterial, the adoption of ASU 2016-18 did not have a material impact on the Company’s condensed consolidated financial statements for the three and six months ended June 30, 2017 . There is no impact to the cash flow statement for the six months ended June 30, 2018 as there was no restricted cash balance as of the beginning or end of the period. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”). ASU 2018-02 allows an entity to reclassify stranded income tax effects resulting from the U.S. Tax Cuts and Jobs Act (the “Act”) from accumulated other comprehensive loss to retained earnings. The amendments in ASU 2018-02 are effective for fiscal years beginning after December 15, 2018, with early adoption permitted, including adoption in any interim period for which financial statements have not yet been issued. The Company adopted and applied the ASU 2018-02 amendments in the second quarter of 2018. The adoption of the ASU 2018-02 amendments resulted in a $0.1 million cumulative-effect adjustment as of April 1, 2018, the first day of the Company’s second quarter of fiscal year 2018, between accumulated other comprehensive loss and retained earnings for the amount of the stranded tax effects. Recently Issued Accounting Pronouncements 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 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 statement of operations, 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 plans to adopt this guidance on January 1, 2019, and expects the adoption will have a material impact on its condensed consolidated balance sheets based on the valuation of right-of-use assets and lease liabilities, previously described as operating leases, calculated as the present value of the Company’s forecasted future lease commitments. The Company is continuing to assess the overall impacts of the new standard, including the discount rate to be applied in these valuations and increased leasing disclosures, as well as policy and process changes to support the new standard.

REVENUE (Tables)

REVENUE (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Deferred Revenue and Accounts Receivable	The opening and closing balances of the Company’s deferred revenue and accounts receivable are as follows (in thousands): Balance at Beginning of Period (1/1/18) (Decrease) / Increase Balance at End of Period Six Months Ended June 30, 2018 Accounts Receivable $ 86,602 (30,203 ) $ 56,399 Deferred Revenue (Current) $ 197 139 $ 336 Deferred Revenue (Non-current) $ 254 2,688 $ 2,942
Schedule of Disaggregation of Revenue	Further disaggregation of revenue by geographic country can be found in Note 13. Three Months Ended As a % of Six Months Ended As a % of June 30, 2018 Total Revenue June 30, 2018 Total Revenue (dollars in thousands) Americas $ 24,012 37 % $ 33,738 24 % EMEA 20,255 31 % 47,899 35 % APAC 20,736 32 % 56,307 41 % Total revenue $ 65,003 100 % $ 137,944 100 %

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 Gross Unrealized Losses Amortized Cost Gains Less than One Year Greater than One Year Estimated Fair Value Cash and Cash Equivalents Marketable Securities Cash $ 73,507 $ — $ — $ — $ 73,507 $ 73,507 $ — Money market funds 20,180 — — — 20,180 20,180 — U.S. treasury bonds 26,509 — (72 ) — 26,437 — 26,437 Commercial paper 44,011 1 (13 ) — 43,999 6,969 37,030 Certificates of deposit 48,418 18 (44 ) — 48,392 — 48,392 Asset-backed securities 38,708 1 (112 ) — 38,597 — 38,597 Corporate debt securities 124,077 9 (416 ) (4 ) 123,666 — 123,666 Total $ 375,410 $ 29 $ (657 ) $ (4 ) $ 374,778 $ 100,656 $ 274,122 December 31, 2017 Gross Unrealized Estimated Cash and Cash Marketable Amortized Cost Gains Losses (1) Fair Value Equivalents Securities Cash $ 43,223 $ — $ — $ 43,223 $ 43,223 $ — Money market funds 11,070 — — 11,070 11,070 — Repurchase agreements 12,500 — — 12,500 12,500 — U.S. treasury bonds 26,316 — (80 ) 26,236 — 26,236 Commercial paper 60,623 — (9 ) 60,614 — 60,614 Certificates of deposit 34,993 6 (33 ) 34,966 — 34,966 Asset-backed securities 33,374 1 (53 ) 33,322 702 32,620 Corporate debt securities 142,960 9 (290 ) 142,679 — 142,679 Total $ 365,059 $ 16 $ (465 ) $ 364,610 $ 67,495 $ 297,115 (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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Proceeds from the sales and maturities of marketable securities $ 77,678 $ 61,400 $ 165,508 $ 100,300 Realized gains $ 1 $ 3 $ 5 $ 4 Realized losses $ (30 ) $ — $ (32 ) $ —
Contractual Maturities of Short-term and Long-Term Marketable Securities Held	The contractual maturities of short-term and long-term marketable securities held at June 30, 2018 and December 31, 2017 are as follows (in thousands): June 30, 2018 December 31, 2017 Amortized Cost Basis Aggregate Fair Value Amortized Cost Basis Aggregate Fair Value Due within one year $ 203,190 $ 202,759 $ 212,137 $ 211,933 Due after one year through three years 71,564 71,363 85,426 85,182 Total $ 274,754 $ 274,122 $ 297,563 $ 297,115

INVENTORY (Tables)

INVENTORY (Tables)	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Raw materials $ 36,033 $ 32,599 Work-in-process 388 965 Finished goods 14,229 28,668 Inventory $ 50,650 $ 62,232

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Engineering laboratory equipment $ 46,851 $ 39,433 Computer software 2,782 2,281 Computer equipment 5,025 4,380 Furniture and fixtures 3,219 3,041 Leasehold improvements 3,547 2,282 Construction in progress 2,499 4,591 Total property and equipment 63,923 56,008 Less: Accumulated depreciation (34,416 ) (27,833 ) Property and equipment, net $ 29,507 $ 28,175

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Employee-related liabilities $ 6,800 $ 5,233 Goods and services received not invoiced 6,285 12,827 Accrued manufacturing related expenses 3,951 4,007 Warranty reserve 7,077 8,306 Other accrued liabilities 9,117 6,861 Accrued liabilities $ 33,230 $ 37,234

FAIR VALUE MEASUREMENT (Tables)

FAIR VALUE MEASUREMENT (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 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 $ — $ 20,180 $ — $ 20,180 U.S. treasury bonds — 26,437 — 26,437 Commercial paper — 43,999 — 43,999 Certificates of deposit — 48,392 — 48,392 Asset-backed securities — 38,597 — 38,597 Corporate debt securities — 123,666 — 123,666 Total $ — $ 301,271 $ — $ 301,271 December 31, 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 $ — $ 11,070 $ — $ 11,070 Repurchase agreements — 12,500 — 12,500 U.S. treasury bonds — 26,236 — 26,236 Commercial paper — 60,614 — 60,614 Certificates of deposit — 34,966 — 34,966 Asset-backed securities — 33,322 — 33,322 Corporate debt securities — 142,679 — 142,679 Total $ — $ 321,387 $ — $ 321,387

STOCK COMPENSATION PLANS (Table

STOCK COMPENSATION PLANS (Tables)	6 Months Ended
	Jun. 30, 2018
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 statements of operations for the three and six months ended June 30, 2018 and 2017 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cost of revenue $ 572 $ 511 $ 1,093 $ 953 Research and development 4,467 3,779 8,255 6,771 Sales, general and administrative 2,549 1,820 4,778 3,018 Total stock-based compensation $ 7,588 $ 6,110 $ 14,126 $ 10,742
Schedule of Stock-Based Compensation Expense by Award Type	The following table summarizes stock-based compensation expense by award type for the three and six months ended June 30, 2018 and 2017 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Stock options $ 588 $ 655 $ 1,189 $ 1,321 Restricted stock units 6,690 5,126 12,285 8,812 Employee stock purchase plan 285 300 583 551 Other awards 25 29 69 58 Total stock-based compensation $ 7,588 $ 6,110 $ 14,126 $ 10,742
Stock Option Activity	A summary of stock option activity under the Company’s equity incentive plans for the six months ended June 30, 2018 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, 2017 1,634 $ 8.34 6.6 $ 47,356 Granted 10 $ 28.77 Exercised (348 ) $ 4.37 $ 11,103 Cancelled (31 ) $ 11.47 Outstanding at June 30, 2018 1,265 $ 9.52 6.2 $ 33,915 Vested and expected to vest at: June 30, 2018 1,265 $ 9.52 6.2 $ 33,915 December 31, 2017 1,634 $ 8.34 6.6 $ 47,356 Exercisable at: June 30, 2018 785 $ 6.65 5.6 $ 22,953 December 31, 2017 907 $ 5.28 5.9 $ 28,634
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 2.3% Expected dividend yield None Expected volatility 51.4% Expected term (in years) 2.9 Grant date fair value of underlying shares $39.02
Summary of Changes in Company's RSU	A summary of the changes in the Company’s RSUs during the six months ended June 30, 2018 is as follows: RSUs (in thousands) Weighted-Average Grant Date Fair Value Outstanding at December 31, 2017 2,288 $ 36.08 Granted 704 $ 41.51 Vested (485 ) $ 29.29 Cancelled (12 ) $ 26.76 Outstanding at June 30, 2018 2,495 $ 38.98

NET (LOSS) INCOME PER SHARE (Ta

NET (LOSS) INCOME PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net (Loss) Income Per Share	The following table sets forth the computation of the Company’s basic and diluted net (loss) income per share (in thousands, except per share amounts): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Numerator: Net (loss) income $ (3,245 ) $ 4,664 $ (12,323 ) $ 40,373 Denominator: Weighted-average shares used to compute net (loss) income per share - basic 40,307 38,756 40,074 38,546 Dilutive effect of stock options, unvested restricted stock and restricted stock units and employee stock purchase plan — 2,826 — 3,093 Weighted-average shares used to compute net (loss) income per share - diluted 40,307 41,582 40,074 41,639 Net (loss) income per share Basic $ (0.08 ) $ 0.12 $ (0.31 ) $ 1.05 Diluted $ (0.08 ) $ 0.11 $ (0.31 ) $ 0.97
Summary of Common Stock Equivalents Excluded from Computation of Diluted Net Income (Loss) Per Share	The following common stock equivalents (in thousands) were excluded from the computation of diluted net (loss) income per share for the periods presented because including them would have been antidilutive: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Options to purchase common stock 1,030 90 1,126 90 Unvested restricted stock units and awards 1,699 562 1,665 381 Employee stock purchase plan 72 — 72 —

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Future Annual Minimum Lease Payments	Future minimum lease payments due under these non-cancelable lease agreements as of June 30, 2018 , are as follows (in thousands): Amounts Remaining 2018 $ 1,687 2019 3,423 2020 3,452 2021 3,294 2022 2,410 Thereafter 5,546 Total $ 19,812
Schedule of Changes in Product Warrant Liability	Changes in the Company’s 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): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Warranty reserve, beginning of period $ 7,418 $ 2,113 $ 8,306 $ 2,158 Provisions made to warranty reserve during the period 2,561 4,771 6,024 5,971 Charges against warranty reserve during the period (2,902 ) (2,025 ) (7,253 ) (3,270 ) Warranty reserve, end of period $ 7,077 $ 4,859 $ 7,077 $ 4,859

SEGMENT INFORMATION AND GEOGR36

SEGMENT INFORMATION AND GEOGRAPHIC DATA (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Summary of Revenue by Geographic Region	Revenue by geographic region, based on ship-to destinations, which in certain instances may be the location of a contract manufacturer rather than the Company’s end customer, was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 United States $ 23,159 $ 23,814 $ 32,586 $ 36,227 China 12,909 29,367 34,993 86,349 Germany 10,086 9,649 29,832 22,615 Thailand 4,853 5,115 11,972 16,719 Other 13,996 10,953 28,561 31,655 Total revenue $ 65,003 $ 78,898 $ 137,944 $ 193,565
Summary of Total Long-Lived Assets by Geographic Region	Total long-lived assets by geographic region consisted of the following as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 United States $ 19,969 $ 19,065 China 1,740 1,165 Thailand 5,409 7,065 Other 2,389 880 Total long-lived assets $ 29,507 $ 28,175

CONCENTRATIONS OF RISK (Tables)

CONCENTRATIONS OF RISK (Tables)	6 Months Ended
	Jun. 30, 2018
Risks and Uncertainties [Abstract]
Summary of Concentrations of Risk	For the three and six months ended June 30, 2018 and 2017 , total purchases from each of the suppliers were as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 W * 11 % * 30 % X 12 % 20 % 15 % 23 % Y 47 % * 44 % 28 % Z * 12 % * 17 % * Less than 10% of total purchases in the period indicated Customers with revenue equal to or greater than 10% of total revenue for the three and six months ended June 30, 2018 and 2017 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 A (1) * 28 % 14 % 36 % B 18 % 19 % 18 % 14 % C 14 % 15 % 17 % * D 12 % * * * * Less than 10% of revenue in the period indicated (1) Customer A was subject to U.S. Department of Commerce restrictions that prevented sales to this customer from April 15, 2018 through July 13, 2018. Customers that accounted for equal to or greater than 10% of accounts receivable at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 A (1) * 15 % B 14 % 10 % C 16 % 19 % * Less than 10% of accounts receivable at the date indicated (1) Customer A was subject to U.S. Department of Commerce restrictions that prevented sales to this customer from April 15, 2018 through July 13, 2018.

NATURE OF THE BUSINESS AND OP38

NATURE OF THE BUSINESS AND OPERATIONS (Details)	6 Months Ended
	Jun. 30, 2018GBTB
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Optical interconnect modules transmission speed | TB	1.2
Minimum
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Optical interconnect modules transmission speed	100
Maximum
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Optical interconnect modules transmission speed	400

BASIS OF PRESENTATION AND SUM39

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Apr. 01, 2018	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Prepaid expenses and other current assets	$ 21,053					$ 18,985
Retained earnings	165,301					177,422
Increase in prepaid expenses and other current assets	2,236	$ 6,721
Accumulated other comprehensive loss	$ 515					$ 320
Reclassifications
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Decrease in deferred product cost		300
Increase in prepaid expenses and other current assets		$ 300
ASU 2018-02
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings			$ 100
Accumulated other comprehensive loss				$ 100
Cumulative effect of applying ASC 606 | ASU 2014-09
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings					$ 200

REVENUE - Narrative (Details)

REVENUE - Narrative (Details)	6 Months Ended
	Jun. 30, 2018USD ($)
Disaggregation of Revenue [Line Items]
Capitalized contracts	$ 0
Minimum
Disaggregation of Revenue [Line Items]
Standard warranty period	12 months
Payment terms on invoiced amounts	30 days
Maximum
Disaggregation of Revenue [Line Items]
Standard warranty period	24 months
Payment terms on invoiced amounts	60 days

REVENUE - Deferred Revenue and

REVENUE - Deferred Revenue and Accounts Receivable (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Accounts receivable	$ 56,399		$ 86,602	$ 86,602
Deferred Revenue (Current)	336		197	$ 573
Deferred Revenue (Non-current)	2,942		$ 254
Increase / (Decrease), Accounts Receivable	(30,203)	$ (25,216)
Increase / (Decrease), Deferred Revenue (Current)	139
Increase / (Decrease), Deferred Revenue (Non-current)	$ 2,688

REVENUE - Disaggregation of Rev

REVENUE - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 65,003	$ 78,898	$ 137,944	$ 193,565
Revenue, as a % of Total Revenue	100.00%		100.00%
Americas
Disaggregation of Revenue [Line Items]
Revenue	$ 24,012		$ 33,738
Revenue, as a % of Total Revenue	37.00%		24.00%
EMEA
Disaggregation of Revenue [Line Items]
Revenue	$ 20,255		$ 47,899
Revenue, as a % of Total Revenue	31.00%		35.00%
APAC
Disaggregation of Revenue [Line Items]
Revenue	$ 20,736		$ 56,307
Revenue, as a % of Total Revenue	32.00%		41.00%

FINANCIAL INSTRUMENTS - Schedul

FINANCIAL INSTRUMENTS - Schedule of Cash, Cash Equivalents and Short- and Long-term Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	$ 375,410	$ 365,059
Gross Unrealized Gains	29	16
Gross Unrealized Losses, Less than One Year	(657)
Gross Unrealized Losses, Greater than One Year	(4)
Gross Unrealized Losses		(465)
Estimated Fair Value	374,778	364,610
Cash and Cash Equivalents	100,656	67,495
Marketable Securities	274,122	297,115
Corporate debt securities
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	124,077	142,960
Gross Unrealized Gains	9	9
Gross Unrealized Losses, Less than One Year	(416)
Gross Unrealized Losses, Greater than One Year	(4)
Gross Unrealized Losses		(290)
Estimated Fair Value	123,666	142,679
Cash and Cash Equivalents	0	0
Marketable Securities	123,666	142,679
Cash
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	73,507	43,223
Gross Unrealized Gains	0	0
Gross Unrealized Losses, Less than One Year	0
Gross Unrealized Losses, Greater than One Year	0
Gross Unrealized Losses		0
Estimated Fair Value	73,507	43,223
Cash and Cash Equivalents	73,507	43,223
Marketable Securities	0	0
Money market funds
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	20,180	11,070
Gross Unrealized Gains	0	0
Gross Unrealized Losses, Less than One Year	0
Gross Unrealized Losses, Greater than One Year	0
Gross Unrealized Losses		0
Estimated Fair Value	20,180	11,070
Cash and Cash Equivalents	20,180	11,070
Marketable Securities	0	0
Repurchase agreements
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost		12,500
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Value		12,500
Cash and Cash Equivalents		12,500
Marketable Securities		0
U.S. treasury bonds
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	26,509	26,316
Gross Unrealized Gains	0	0
Gross Unrealized Losses, Less than One Year	(72)
Gross Unrealized Losses, Greater than One Year	0
Gross Unrealized Losses		(80)
Estimated Fair Value	26,437	26,236
Cash and Cash Equivalents	0	0
Marketable Securities	26,437	26,236
Commercial paper
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	44,011	60,623
Gross Unrealized Gains	1	0
Gross Unrealized Losses, Less than One Year	(13)
Gross Unrealized Losses, Greater than One Year	0
Gross Unrealized Losses		(9)
Estimated Fair Value	43,999	60,614
Cash and Cash Equivalents	6,969	0
Marketable Securities	37,030	60,614
Certificates of deposit
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	48,418	34,993
Gross Unrealized Gains	18	6
Gross Unrealized Losses, Less than One Year	(44)
Gross Unrealized Losses, Greater than One Year	0
Gross Unrealized Losses		(33)
Estimated Fair Value	48,392	34,966
Cash and Cash Equivalents	0	0
Marketable Securities	48,392	34,966
Asset-backed securities
Schedule Of Cash Cash Equivalents And Marketable Securities [Line Items]
Amortized Cost	38,708	33,374
Gross Unrealized Gains	1	1
Gross Unrealized Losses, Less than One Year	(112)
Gross Unrealized Losses, Greater than One Year	0
Gross Unrealized Losses		(53)
Estimated Fair Value	38,597	33,322
Cash and Cash Equivalents	0	702
Marketable Securities	$ 38,597	$ 32,620

FINANCIAL INSTRUMENTS - Proceed

FINANCIAL INSTRUMENTS - Proceeds from Sales and Maturities of Marketable Securities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Proceeds from the sales and maturities of marketable securities	$ 77,678	$ 61,400	$ 165,508	$ 100,300
Realized gains	1	3	5	4
Realized losses	$ (30)	$ 0	$ (32)	$ 0

FINANCIAL INSTRUMENTS - Contrac

FINANCIAL INSTRUMENTS - Contractual Maturities of Short-term and Long-term Marketable Securities Held (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Amortized Cost Basis
Due within one year	$ 203,190	$ 212,137
Due after one year through three years	71,564	85,426
Amortized Cost Basis	274,754	297,563
Aggregate Fair Value
Due within one year	202,759	211,933
Due after one year through three years	71,363	85,182
Aggregate Fair Value	$ 274,122	$ 297,115

INVENTORY - Schedule of Invento

INVENTORY - Schedule of Inventory (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials		$ 36,033	$ 32,599
Work-in-process		388	965
Finished goods		14,229	28,668
Inventory		$ 50,650	$ 62,232
Inventory write-offs	$ 3,900

PROPERTY AND EQUIPMENT - Schedu

PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 63,923	$ 56,008
Less: Accumulated depreciation	(34,416)	(27,833)
Property and equipment, net	29,507	28,175
Engineering laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	46,851	39,433
Computer software
Property, Plant and Equipment [Line Items]
Total property and equipment	2,782	2,281
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	5,025	4,380
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	3,219	3,041
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	3,547	2,282
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 2,499	$ 4,591

PROPERTY AND EQUIPMENT - Narrat

PROPERTY AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 3,400	$ 3,000	$ 6,634	$ 5,841

ACCRUED LIABILITIES - Schedule

ACCRUED LIABILITIES - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Employee-related liabilities	$ 6,800		$ 5,233
Goods and services received not invoiced	6,285		12,827
Accrued manufacturing related expenses	3,951		4,007
Warranty reserve	7,077	$ 7,418	8,306	$ 4,859	$ 2,113	$ 2,158
Other accrued liabilities	9,117		6,861
Accrued liabilities	33,230		37,234
ZTE Kangxun Telecom Co. Ltd
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accrued manufacturing related expenses	$ 2,000
Reclassifications
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Other accrued liabilities			100
Outsourced foundry services			$ 100

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	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 301,271	$ 321,387
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	301,271	321,387
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		12,500
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		12,500
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	26,437	26,236
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	26,437	26,236
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	43,999	60,614
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	43,999	60,614
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	48,392	34,966
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	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	48,392	34,966
Certificates of deposit | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	38,597	33,322
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	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	38,597	33,322
Asset-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	123,666	142,679
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	123,666	142,679
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	20,180	11,070
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	20,180	11,070
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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Transfers between fair value measurement levels	$ 0	$ 0	$ 0	$ 0

STOCK COMPENSATION PLANS - Clas

STOCK COMPENSATION PLANS - Classification of Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 7,588	$ 6,110	$ 14,126	$ 10,742
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	572	511	1,093	953
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	4,467	3,779	8,255	6,771
Sales, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 2,549	$ 1,820	$ 4,778	$ 3,018

STOCK COMPENSATION PLANS - Sche

STOCK COMPENSATION PLANS - Schedule of Stock-Based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 7,588	$ 6,110	$ 14,126	$ 10,742
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	285	300	583	551
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	588	655	1,189	1,321
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	6,690	5,126	12,285	8,812
Other awards
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 25	$ 29	$ 69	$ 58

STOCK COMPENSATION PLANS - Stoc

STOCK COMPENSATION PLANS - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Number of Options, Abstract
Number of options outstanding at beginning of period (in shares)	1,634
Number of options granted (in shares)	10
Number of options exercised (in shares)	(348)
Number of options cancelled (in shares)	(31)
Number of options outstanding at end of period (in shares)	1,265	1,634
Number of options vested and expected to vest (in shares)	1,265	1,634
Number of options exercisable (in shares)	785	907
Weighted-Average Exercise Price, Abstract
Weighted-average exercise price outstanding at beginning of period (in USD per share)	$ 8.34
Options granted, Weighted-average exercise price (in USD per share)	28.77
Options exercised, Weighted-average exercise price (in USD per share)	4.37
Options cancelled, Weighted-average exercise price (in USD per share)	11.47
Weighted-average exercise price outstanding at end of period (in USD per share)	9.52	$ 8.34
Options vested and expected to vest, Weighted-average exercise price (in USD per share)	9.52	8.34
Options exercisable, Weighted-average exercise price (in USD per share)	$ 6.65	$ 5.28
Weighted-Average Remaining Contract Term, Abstract
Options outstanding, Weighted-average remaining contractual term (in years)	6 years 2 months 12 days	6 years 7 months 6 days
Options vested and expected to vest, Weighted-average remaining contractual term (in years)	6 years 2 months 12 days	6 years 7 months 6 days
Options exercisable, Weighted-average remaining contractual term (in years)	5 years 7 months 6 days	5 years 10 months 24 days
Aggregate Intrinsic Value, Abstract
Options outstanding, Aggregate intrinsic value at beginning of period	$ 47,356
Options exercised, Aggregate intrinsic value	11,103
Options outstanding, Aggregate intrinsic value at end of period	33,915	$ 47,356
Options vested and expected to vest, Aggregate intrinsic value	33,915	47,356
Options exercisable, Aggregate intrinsic value	$ 22,953	$ 28,634

STOCK COMPENSATION PLANS - Narr

STOCK COMPENSATION PLANS - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 28, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of stock options granted (in USD per share)		$ 15.58		$ 15.58
Number of options granted (in shares)				10,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost, stock options		$ 3,600,000		$ 3,600,000		$ 4,800,000
Weighted average recognition period				1 year 9 months 18 days		2 years 2 months 12 days
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				2 years 9 months 18 days		2 years 10 months 24 days
Restricted stock units granted (in shares)				704,000
Vested awards settled in cash				$ 0
Unrecognized stock-based compensation expense		$ 61,900,000		$ 61,900,000		$ 47,800,000
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)				613,000
Awards vesting period				4 years
Performance-Based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Right to receive common stock upon achievement of vesting conditions (in shares)				1
Performance-Based RSUs | Executive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted (in shares)	90,808			90,808
Performance-Based RSUs | Executive | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted (in shares)				90,808
Earned PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance objective period				3 years

STOCK COMPENSATION PLANS - Weig

STOCK COMPENSATION PLANS - Weighted-Average Assumptions Used to Estimate Fair Value (Details) - Performance-Based RSUs	6 Months Ended
	Jun. 30, 2018$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.30%
Expected dividend yield	0.00%
Expected volatility	51.40%
Expected term (in years)	2 years 10 months 24 days
Grant date fair value of underlying shares (in USD per share)	$ 39.02

STOCK COMPENSATION PLANS - Chan

STOCK COMPENSATION PLANS - Changes in Company Restricted Stock Units (Details) - Restricted stock units shares in Thousands	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Shares outstanding at beginning of period (in shares) | shares	2,288
Granted (in shares) | shares	704
Vested (in shares) | shares	(485)
Cancelled (in shares) | shares	(12)
Shares outstanding at end of period (in shares) | shares	2,495
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 beginning of period (in USD per share) | $ / shares	$ 36.08
Granted, Weighted-average grant date fair value (in USD per share) | $ / shares	41.51
Vested, Weighted-average grant date fair value (in USD per share) | $ / shares	29.29
Cancelled, Weighted-average grant date fair value (in USD per share) | $ / shares	26.76
Shares outstanding, Weighted-average grant date fair value at end of period (in USD per share) | $ / shares	$ 38.98

NET (LOSS) INCOME PER SHARE - C

NET (LOSS) INCOME PER SHARE - Computation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net (loss) income	$ (3,245)	$ 4,664	$ (12,323)	$ 40,373
Denominator:
Weighted-average shares used to compute net (loss) income per share - basic (in shares)	40,307	38,756	40,074	38,546
Dilutive effect of stock options, unvested restricted stock and restricted stock units and employee stock purchase plan (in shares)	0	2,826	0	3,093
Weighted-average shares used to compute net (loss) income per share - diluted (in shares)	40,307	41,582	40,074	41,639
Net (loss) income per share
Basic (in USD per share)	$ (0.08)	$ 0.12	$ (0.31)	$ 1.05
Diluted (in USD per share)	$ (0.08)	$ 0.11	$ (0.31)	$ 0.97

NET (LOSS) INCOME PER SHARE - S

NET (LOSS) INCOME PER SHARE - Summary of Common Stock Equivalents Excluded from Computation of Diluted Net Income Per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
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)	1,030	90	1,126	90
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)	1,699	562	1,665	381
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)	72	0	72	0

NET (LOSS) INCOME PER SHARE - N

NET (LOSS) INCOME PER SHARE - Narrative (Details) - shares	1 Months Ended	6 Months Ended
	Feb. 28, 2018	Jun. 30, 2018
Performance-Based RSUs | Executive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted (in shares)	90,808	90,808

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details)	Mar. 29, 2018	Nov. 07, 2017lawsuit	May 31, 2017contract_manufacturerAC400_UnitCFP_Unit	Dec. 31, 2017USD ($)lawsuit	Sep. 30, 2017lawsuit	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)
Loss Contingencies [Line Items]
Operating leases rent expense | $						$ 1,200,000	$ 1,200,000	$ 2,400,000	$ 2,700,000
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
Duration of quality issue at contract manufacturer			4 months
Contract manufacturer quality issue | AC400 Unit
Loss Contingencies [Line Items]
Defective AC400 units | AC400_Unit			1,300
Contract manufacturer quality issue | CFP Unit
Loss Contingencies [Line Items]
Defective AC400 units | CFP_Unit			5,100
Indemnification
Loss Contingencies [Line Items]
Amount accrued | $				$ 0		$ 0		$ 0
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
Pending Litigation | Tharp; Zhang; Kebler v. Acacia Communications, Inc. et al.
Loss Contingencies [Line Items]
Number of lawsuits					3
Pending Litigation | Rollhaus; Tharp; Zhang; Kebler v. Acacia Communications, Inc. et al.
Loss Contingencies [Line Items]
Number of lawsuits		4
Additional days to file motion	30 days
Pending Litigation | Colgan; Wong; Dennis; Farah v. Shanmurgaraj et al.
Loss Contingencies [Line Items]
Number of lawsuits				3

COMMITMENTS AND CONTINGENCIES62

COMMITMENTS AND CONTINGENCIES - Future Annual Minimum Lease Payments (Details) $ in Thousands	Jun. 30, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remaining 2,018	$ 1,687
2,019	3,423
2,020	3,452
2,021	3,294
2,022	2,410
Thereafter	5,546
Total	$ 19,812

COMMITMENTS AND CONTINGENCIES63

COMMITMENTS AND CONTINGENCIES - Schedule of Changes in Product Warrant Liability (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Movement in Standard Product Warranty Accrual [Roll Forward]
Warranty reserve, beginning of period	$ 7,418	$ 2,113	$ 8,306	$ 2,158
Provisions made to warranty reserve during the period	2,561	4,771	6,024	5,971
Charges against warranty reserve during the period	(2,902)	(2,025)	(7,253)	(3,270)
Warranty reserve, end of period	$ 7,077	$ 4,859	$ 7,077	$ 4,859

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Provisional income tax expense under SAB 118					$ 31,400
Benefit from income taxes	$ 7,574	$ 10,511	$ 11,875	$ 15,932
Effective income tax rate	70.00%	179.80%	49.10%	(65.20%)
Uncertain tax positions	$ 4,700		$ 4,700		4,500
Unrecognized tax benefits that, if recognized, would favorably impact effective tax rate	$ 1,900		$ 1,900		$ 2,300

SEGMENT INFORMATION AND GEOGR65

SEGMENT INFORMATION AND GEOGRAPHIC DATA - Narrative (Details)	6 Months Ended
	Jun. 30, 2018segment
Segment Reporting [Abstract]
Number of operating segments	1

SEGMENT INFORMATION AND GEOGR66

SEGMENT INFORMATION AND GEOGRAPHIC DATA - Summary of Revenue by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenue	$ 65,003	$ 78,898	$ 137,944	$ 193,565
United States
Segment Reporting Information [Line Items]
Revenue	23,159	23,814	32,586	36,227
China
Segment Reporting Information [Line Items]
Revenue	12,909	29,367	34,993	86,349
Germany
Segment Reporting Information [Line Items]
Revenue	10,086	9,649	29,832	22,615
Thailand
Segment Reporting Information [Line Items]
Revenue	4,853	5,115	11,972	16,719
Other
Segment Reporting Information [Line Items]
Revenue	$ 13,996	$ 10,953	$ 28,561	$ 31,655

SEGMENT INFORMATION AND GEOGR67

SEGMENT INFORMATION AND GEOGRAPHIC DATA - Summary of Total Long-Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total long-lived assets	$ 29,507	$ 28,175
United States
Segment Reporting Information [Line Items]
Total long-lived assets	19,969	19,065
China
Segment Reporting Information [Line Items]
Total long-lived assets	1,740	1,165
Thailand
Segment Reporting Information [Line Items]
Total long-lived assets	5,409	7,065
Other
Segment Reporting Information [Line Items]
Total long-lived assets	$ 2,389	$ 880

CONCENTRATIONS OF RISK - Summar

CONCENTRATIONS OF RISK - Summary of Customer Concentration of Total Revenue (Details) - Customer Concentration Risk - Revenue	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage		28.00%	14.00%	36.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	18.00%	19.00%	18.00%	14.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%	15.00%	17.00%
Customer D
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%

CONCENTRATIONS OF RISK - Summ69

CONCENTRATIONS OF RISK - Summary of Customer Concentration of Accounts Receivable (Details) - Customer Concentration Risk - Accounts Receivable	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage		15.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%	10.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	16.00%	19.00%

CONCENTRATIONS OF RISK - Summ70

CONCENTRATIONS OF RISK - Summary of Supplier Concentration (Details) - Supplier Concentration Risk - Purchases	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Supplier W
Concentration Risk [Line Items]
Concentration risk, percentage		11.00%		30.00%
Supplier X
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%	20.00%	15.00%	23.00%
Supplier Y
Concentration Risk [Line Items]
Concentration risk, percentage	47.00%		44.00%	28.00%
Supplier Z
Concentration Risk [Line Items]
Concentration risk, percentage		12.00%		17.00%

CONCENTRATIONS OF RISK - Narrat

CONCENTRATIONS OF RISK - Narrative (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Vendor A | Supplier Concentration Risk | Research and development
Concentration Risk [Line Items]
Concentration risk, percentage	21.00%	12.00%

RELATED PARTIES - Narrative (De

RELATED PARTIES - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
ADI
Related Party Transaction [Line Items]
Purchase from related party		$ 700,000	$ 1,000,000	$ 1,400,000	$ 2,200,000
Product development agreement	$ 2,000,000
Product development agreement costs incurred		0		500,000
M/A-COM
Related Party Transaction [Line Items]
Purchase from related party		$ 0		$ 300,000