Vicor (VICR) 10-Q 31 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 20, 2017
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	VICR
Entity Registrant Name	VICOR CORP
Entity Central Index Key	751,978
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		27,581,137
Class B Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		11,758,218

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 48,936	$ 56,170
Accounts receivable, less allowance of $161 in 2017 and $153 in 2016	33,811	25,216
Inventories, net	33,883	27,136
Other current assets	3,470	3,250
Total current assets	120,100	111,772
Long-term deferred tax assets, net	21	38
Long-term investments, net	2,599	2,508
Property, plant and equipment, net	41,248	37,574
Other assets	2,108	2,175
Total assets	166,076	154,067
Current liabilities:
Accounts payable	11,508	7,588
Accrued compensation and benefits	8,939	8,965
Accrued expenses	2,311	2,179
Income taxes payable	252	92
Deferred revenue	8,769	3,403
Total current liabilities	31,779	22,227
Long-term deferred revenue	321	374
Contingent consideration obligations	78	253
Long-term income taxes payable	191	196
Other long-term liabilities	90
Total liabilities	32,459	23,050
Commitments and contingencies (Note 9)
Vicor Corporation stockholders' equity:
Common Stock	400	397
Additional paid-in capital	180,132	176,344
Retained earnings	91,994	93,438
Accumulated other comprehensive loss	(397)	(561)
Treasury stock, at cost	(138,927)	(138,927)
Total Vicor Corporation stockholders' equity	133,320	130,809
Noncontrolling interest	297	208
Total equity	133,617	131,017
Total liabilities and equity	166,076	154,067
Class B Common Stock [Member]
Vicor Corporation stockholders' equity:
Common Stock	$ 118	$ 118

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 161	$ 153

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net revenues	$ 56,888	$ 53,227	$ 169,059	$ 152,195
Cost of revenues	31,745	27,304	94,334	82,485
Gross margin	25,143	25,923	74,725	69,710
Operating expenses:
Selling, general and administrative	14,500	13,312	43,059	41,643
Research and development	10,543	10,338	33,482	31,824
Total operating expenses	25,043	23,650	76,541	73,467
Income (loss) from operations	100	2,273	(1,816)	(3,757)
Other income (expense), net:
Total unrealized gains on available-for-sale securities, net	34	1	91	54
Portion of losses (gains) recognized in other comprehensive income (loss)	(31)	2	(82)	(44)
Net credit gains recognized in earnings	3	3	9	10
Other income (expense), net	306	208	985	340
Total other income (expense), net	309	211	994	350
Income (loss) before income taxes	409	2,484	(822)	(3,407)
Less: Provision for income taxes	371	133	539	168
Consolidated net income (loss)	38	2,351	(1,361)	(3,575)
Less: Net income (loss) attributable to noncontrolling interest	49	15	83	(16)
Net income (loss) attributable to Vicor Corporation	$ (11)	$ 2,336	$ (1,444)	$ (3,559)
Net income (loss) per common share attributable to Vicor Corporation:
Basic	$ 0	$ 0.06	$ (0.04)	$ (0.09)
Diluted	$ 0	$ 0.06	$ (0.04)	$ (0.09)
Shares used to compute net income (loss) per common share attributable to Vicor Corporation:
Basic	39,288	38,837	39,177	38,811
Diluted	39,288	39,184	39,177	38,811

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Consolidated net income (loss)		$ 38	$ 2,351	$ (1,361)	$ (3,575)
Foreign currency translation (losses) gains, net of tax	[1]	(16)	56	88	473
Unrealized gains (losses) on available-for-sale securities, net of tax	[1]	31	(2)	82	44
Other comprehensive income		15	54	170	517
Consolidated comprehensive income (loss)		53	2,405	(1,191)	(3,058)
Less: Comprehensive income attributable to noncontrolling interest		47	19	89	20
Comprehensive income (loss) attributable to Vicor Corporation		$ 6	$ 2,386	$ (1,280)	$ (3,078)
[1]	The deferred tax assets associated with cumulative foreign currency translation (losses) gains and cumulative unrealized gains (losses) on available for sale securities are completely offset by a tax valuation allowance as of September 30, 2017 and 2016. Therefore, there is no income tax benefit (provision) recognized for the three and nine months ended September 30, 2017 and 2016.

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (Parenthetical) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Recognized income tax benefit (provision)	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Consolidated net loss	$ (1,361)	$ (3,575)
Adjustments to reconcile consolidated net loss to net cash provided by (used for) operating activities:
Depreciation and amortization	6,590	6,384
Stock-based compensation expense, net	1,272	171
Increase in other assets		(505)
Increase in other long-term liabilities	90
Decrease in long-term deferred revenue	(53)	(76)
(Gain) loss on disposal of equipment	(15)	4
Deferred income taxes	17	(51)
Credit gain on available-for-salesecurities	(9)	(10)
Provision (benefit) for doubtful accounts	8	(22)
Decrease in long-term income taxes payable	(5)	(10)
Change in current assets and liabilities, net	(5,896)	(3,894)
Net cash provided by (used for) operating activities	638	(1,584)
Investing activities:
Additions to property, plant and equipment	(10,164)	(6,368)
Proceeds from sale of equipment	15	2
Increase in other assets	(17)	(18)
Net cash used for investing activities	(10,166)	(6,384)
Financing activities:
Proceeds from issuance of Common Stock	2,510	455
Payment of contingent consideration obligations	(175)	(64)
Acquisition of noncontrolling interest		(372)
Net cash provided by financing activities	2,335	19
Effect of foreign exchange rates on cash	(41)	35
Net decrease in cash and cash equivalents	(7,234)	(7,914)
Cash and cash equivalents at beginning of period	56,170	62,980
Cash and cash equivalents at end of period	$ 48,936	$ 55,066

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	1. Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements of Vicor Corporation and its consolidated subsidiaries (collectively, the “Company”) have been prepared in accordance with generally accepted accounting principles for interim financial information and pursuant to the rules and regulations of the Securities and Exchange Commission. Accordingly, these interim financial statements do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. Operating results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for any other interim period or the year ending December 31, 2017. The balance sheet at December 31, 2016 presented herein has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. For further information, refer to the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K

Long-Term Investments

Long-Term Investments	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Long-Term Investments	2. Long-Term Investments As of September 30, 2017 and December 31, 2016, the Company held one auction rate security with a par value of $3,000,000, purchased through and held in custody by a broker-dealer affiliate of Bank of America, N.A., that has experienced failed auctions (the “Failed Auction Security”) since February 2008. The Failed Auction Security held by the Company is Aaa/AA+ rated by major credit rating agencies, is collateralized by student loans, and is guaranteed by the U.S. Department of Education under the Federal Family Education Loan Program. Management is not aware of any reason to believe the issuer of the Failed Auction Security is presently at risk of default. Through September 30, 2017, the Company has continued to receive interest payments on the Failed Auction Security in accordance with the terms of its indenture. Management believes the Company ultimately should be able to liquidate the Failed Auction Security without significant loss primarily due to the overall quality of the issue held and the collateral securing the substantial majority of the underlying obligation. However, current conditions in the auction rate securities market have led management to conclude the recovery period for the Failed Auction Security exceeds 12 months. As a result, the Company continued to classify the Failed Auction Security as long-term as of September 30, 2017. The following is a summary of available-for-sale September 30, 2017 Cost Gross Gross Estimated Failed Auction Security $ 3,000 $ — $ 401 $ 2,599 December 31, 2016 Cost Gross Gross Estimated Failed Auction Security $ 3,000 $ — $ 492 $ 2,508 As of September 30, 2017, the Failed Auction Security had been in an unrealized loss position for greater than 12 months. Based on the fair value measurements described in Note 3, the fair value of the Failed Auction Security on September 30, 2017, with a par value of $3,000,000, was estimated by the Company to be approximately $2,599,000. The gross unrealized loss of $401,000 on the Failed Auction Security consists of two types of estimated loss: an aggregate credit loss of $50,000 and an aggregate temporary impairment of $351,000. In determining the amount of credit loss, the Company compared the present value of cash flows expected to be collected to the amortized cost basis of the security, considering credit default risk probabilities and changes in credit ratings as significant inputs, among other factors (See Note 3). The following table represents a rollforward of the activity related to the credit loss recognized in earnings on the Failed Auction Security for the nine months ended September 30 (in thousands): 2017 2016 Balance at the beginning of the period $ 59 $ 72 Reductions in the amount related to credit gain for which other-than-temporary impairment was not previously recognized (9 ) (10 ) Balance at the end of the period $ 50 $ 62 At this time, the Company has no intent to sell the impaired Failed Auction Security and does not believe it is more likely than not the Company will be required to sell this security. If current market conditions deteriorate further, the Company may be required to record additional unrealized losses. If the credit rating of the security deteriorates, the Company may be required to adjust the carrying value of the investment through impairment charges recorded in the Condensed Consolidated Statements of Operations, and any such impairment adjustments may be material. Based on the Company’s ability to access cash and cash equivalents and its expected operating cash flows, management does not anticipate the current lack of liquidity associated with the Failed Auction Security held will affect the Company’s ability to execute its current operating plan.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company accounts for certain financial assets at fair value, defined as the price that would be received to sell an asset or paid to transfer a liability (i.e., an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. As such, fair value is a market-based measurement that should be determined based on assumptions market participants would use in pricing an asset or liability. A three-level hierarchy is used to show the extent and level of judgment used to estimate fair value measurements. Assets and liabilities measured at fair value on a recurring basis included the following as of September 30, 2017 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 9,258 $ — $ — $ 9,258 Long-term investments: Failed Auction Security — — 2,599 2,599 Liabilities: Contingent consideration obligations — — (78 ) (78 ) Assets and liabilities measured at fair value on a recurring basis included the following as of December 31, 2016 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 10,114 $ — $ — $ 10,114 Long-term investments: Failed Auction Security — — 2,508 2,508 Liabilities: Contingent consideration obligations — — (253 ) (253 ) As of September 30, 2017, there was insufficient observable auction rate security market information available to determine the fair value of the Failed Auction Security using Level 1 or Level 2 inputs. As such, the Company’s investment in the Failed Auction Security was deemed to require valuation using Level 3 inputs. Management, after consulting with advisors, valued the Failed Auction Security using analyses and pricing models similar to those used by market participants (i.e., buyers, sellers, and the broker-dealers responsible for execution of the Dutch auction pricing mechanism by which each issue’s interest rate was set). Management utilized a probability weighted discounted cash flow (“DCF”) model to determine the estimated fair value of this security as of September 30, 2017. The major assumptions used in preparing the DCF model included: estimates for the amount and timing of future interest and principal payments based on default probability assumptions used to measure the credit loss of 2.0%; the rate of return required by investors to own this type of security in the current environment, which management estimates to be 5.0% above the risk free rate of return; and an estimated timeframe of three to five years for successful auctions for this type of security to occur. In making these assumptions, management considered relevant factors including: the formula applicable to the security defining the interest rate paid to investors in the event of a failed auction (the “Penalty Rate”); forward projections of the interest rate benchmarks specified in such formulas; the likely timing of principal repayments; the probability of full repayment considering the guarantees by the U.S. Department of Education of the underlying student loans, guarantees by other third parties, and additional credit enhancements provided through other means; and publicly available pricing data for recently issued student loan asset-backed securities not subject to auctions. In developing its estimate of the rate of return required by investors to own the security, management compared the Penalty Rate of the Failed Auction Security with yields of actively traded long-term bonds with similar characteristics and, reflecting the limited liquidity for auction rate securities and the discounts to par value seen in recent tender offers by issuers and arm’s length market transactions between informed buyers and sellers, estimated the implied yield (i.e., the discount to par value) necessary to complete a sale of the Failed Auction Security. Management has calculated an increase or decrease in the liquidity risk premium of 5.0% referenced above of 1.0% (i.e., 100 basis points) as used in the model, would decrease or increase, respectively, the fair value of the Failed Auction Security by approximately $100,000. The significant unobservable inputs used in the fair value measurement of the Failed Auction Security are the cumulative probability of earning the maximum rate until maturity, the cumulative probability of principal return prior to maturity, the cumulative probability of default, the liquidity risk premium, and the recovery rate in default. Significant increases (decreases) in any of those inputs in isolation would result in changes in fair value measurement. Significant increases (decreases) in the cumulative probability of earning the maximum rate until maturity, the cumulative probability of principal return prior to maturity, and the recovery rate in default would result in a higher (lower) fair value measurement, while increases (decreases) in the cumulative probability of default and the liquidity risk premium would result in a lower (higher) fair value measurement. Generally, the interrelationships are such that a change in the assumption used for the cumulative probability of principal return prior to maturity is accompanied by a directionally similar change in the assumption used for the cumulative probability of earning the maximum rate until maturity and a directionally opposite change in the assumptions used for the cumulative probability of default and the liquidity risk premium. The recovery rate in default is somewhat independent and based upon the security’s specific underlying assets and published recovery rate indices. Quantitative information about Level 3 fair value measurements as of September 30, 2017 is as follows (dollars in thousands): Fair Valuation Unobservable Input Weighted Failed Auction Security $ 2,599 Discounted cash flow Cumulative probability of earning the maximum rate until maturity 0.04 % Cumulative probability of principal return prior to maturity 94.81 % Cumulative probability of default 5.15 % Liquidity risk premium 5.00 % Recovery rate in default 40.00 % The change in the estimated fair value calculated for the investment valued on a recurring basis utilizing Level 3 inputs (i.e., the Failed Auction Security) for the nine months ended September 30, 2017 was as follows (in thousands): Balance at the beginning of the period $ 2,508 Credit gain on available-for-sale 9 Gain included in Other comprehensive income 82 Balance at the end of the period $ 2,599 The Company has classified its contingent consideration obligations as Level 3 because the fair value for these liabilities was determined using unobservable inputs. The liabilities were based on estimated sales of legacy products over the period of royalty payments at the royalty rate, discounted using the Company’s estimated cost of capital. The change in the estimated fair value calculated for the liabilities valued on a recurring basis utilizing Level 3 inputs (i.e., the Contingent consideration obligations) for the nine months ended September 30, 2017 was as follows (in thousands): Balance at the beginning of the period $ 253 Payments (175 ) Balance at the end of the period $ 78 There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the nine months ended September 30, 2017.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	4. Stock-Based Compensation The Company’s Board of Directors approved the Vicor Corporation 2017 Employee Stock Purchase Plan (the “Plan” or the “ESPP”) on April 26, 2017. The ESPP became effective on June 16, 2017, the date the Company’s stockholders approved the Plan at the 2017 Annual Meeting of Stockholders. The Company has reserved 2,000,000 shares of Common Stock under the Plan for issuance to eligible employees who elect to participate. The ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the Internal Revenue Code. The ESPP operates in successive periods of approximately six months, each referred to as an “offering period.” Generally, offering periods commence on or around September 1 and March 1 and end on or around the following February 28 or August 31, respectively. Under the ESPP, an option is granted to participating employees on the first day of an offering period to purchase shares of the Company’s Common Stock at the end of that offering period at a purchase price equal to 85% of the lesser of the fair market value of a share of Common Stock on either the first day or the last day of that offering period. The purchase of shares is funded by means of periodic payroll deductions, which may not exceed 15.0% of the employee’s eligible compensation, as defined in the Plan. Among other provisions, the Plan limits the number of shares that can be purchased by a participant during any offering period and cumulatively for any calendar year. The Company uses the Black-Scholes option pricing model to calculate the fair value of stock option awards and options granted under the ESPP as of their grant date. Stock-based compensation expense, net for the three and nine months ended September 30 was as follows (in thousands): Three Months Ended Nine Months Ended 2017 2016 2017 2016 Cost of revenues $ 53 $ (47 ) $ 125 $ 59 Selling, general and administrative 466 (327 ) 861 148 Research and development 212 (124 ) 286 (36 ) Total stock-based compensation $ 731 $ (498 ) $ 1,272 $ 171 On December 31, 2010, the Company granted 2,984,250 non-qualified Compensation expense by type of award for the three and nine months ended September 30, was as follows (in thousands): Three Months Ended Nine Months Ended 2017 2016 2017 2016 Stock options $ 689 $ (498 ) $ 1,230 $ 171 ESPP 42 — 42 — Total stock-based compensation $ 731 $ (498 ) $ 1,272 $ 171

Net Income (Loss) per Share

Net Income (Loss) per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Net Income (Loss) per Share	5. Net Income (Loss) per Share The following table sets forth the computation of basic and diluted net income (loss) per share for the three and nine months ended September 30 (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Numerator: Net income (loss) attributable to Vicor Corporation $ (11 ) $ 2,336 $ (1,444 ) $ (3,559 ) Denominator: Denominator for basic net income (loss) per share-weighted average shares (1) 39,288 38,837 39,177 38,811 Effect of dilutive securities: Employee stock options (2) — 347 — — Denominator for diluted net income (loss) per share – adjusted weighted-average shares and assumed conversions 39,288 39,184 39,177 38,811 Basic net income (loss) per share $ (0.00 ) $ 0.06 $ (0.04 ) $ (0.09 ) Diluted net income (loss) per share $ (0.00 ) $ 0.06 $ (0.04 ) $ (0.09 ) (1) Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding. (2) Options to purchase 1,452,808 shares of Common Stock for the three and nine months ended September 30, 2017 were not included in the calculation of net loss per share as the effect would have been antidilutive. Options to purchase 449,464 and 1,845,289 shares of Common Stock for the three and nine months ended September 30, 2016, respectively, were not included in the calculation of net income (loss) per share as the effect would have been antidilutive.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Inventories	6. Inventories Inventories are valued at the lower of cost (determined using the first-in, first-out The Company provides reserves for inventories estimated to be excess, obsolete or unmarketable. The Company’s estimation process for assessing net realizable value is based upon its known backlog, projected future demand, historical consumption and expected market conditions. If the Company’s estimated demand and/or market expectation were to change or if product sales were to decline, the Company’s estimation process may cause larger inventory reserves to be recorded, resulting in larger charges to cost of revenues. Inventories were as follows (in thousands): September 30, 2017 December 31, 2016 Raw materials $ 26,247 $ 18,648 Work-in-process 2,774 3,361 Finished goods 4,862 5,127 Net balance $ 33,883 $ 27,136

Product Warranties

Product Warranties	9 Months Ended
	Sep. 30, 2017
Guarantees and Product Warranties [Abstract]
Product Warranties	7. Product Warranties The Company generally offers a two-year Product warranty activity for the three and nine months ended September 30 was as follows (in thousands): Three Months Ended Nine Months Ended 2017 2016 2017 2016 Balance at the beginning of the period $ 244 $ 496 $ 214 $ 584 Accruals for warranties for products sold in the period 126 61 321 291 Fulfillment of warranty obligations (82 ) (106 ) (179 ) (374 ) Revisions of estimated obligations — (109 ) (68 ) (159 ) Balance at the end of the period $ 288 $ 342 $ 288 $ 342

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes The tax provision is based on the estimated annual effective tax rate for the year, which includes estimated federal, state and foreign income taxes on the Company’s projected pre-tax The provision for income taxes and the effective income tax rates for the three and nine months ended September 30 were as follows (dollars in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Provision for income taxes $ 371 $ 133 $ 539 $ 168 Effective income tax rate 90.7 % 5.4 % 65.6 % 4.9 % The provisions for income taxes in each 2017 and 2016 period were primarily due to estimated foreign income taxes and for estimated state taxes in jurisdictions in which the Company does not have net operating loss carryforwards. No tax benefit could be recognized for the majority of the Company’s losses during the periods due to a full valuation allowance against all net domestic deferred tax assets. In connection with the Company’s acquisition of 100% ownership of certain operating assets and cash of the Company’s consolidated subsidiary, Converpower Corporation, the related deferred tax liability for unremitted earnings of $55,000 was reversed and recorded as a discrete benefit in the first quarter of 2016. As described in Note 11- As of September 30, 2017, the Company continues to maintain a valuation allowance of approximately $32,746,000 against all domestic net deferred tax assets and the majority of foreign net deferred tax assets, for which realization cannot be considered more likely than not at this time. In May 2017, the Company received notice from the Internal Revenue Service that its federal corporate tax return for tax year 2015 had been selected for examination. The examination is ongoing.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies At September 30, 2017, the Company had approximately $3,006,000 of capital expenditure commitments. On January 28, 2011, SynQor, Inc. (“SynQor”) filed a complaint for patent infringement against Ericsson, Inc. (“Ericsson”), Cisco Systems, Inc. (“Cisco”) and the Company in the U.S. District Court for the Eastern District of Texas (the “Texas Action”). Ericsson and Cisco subsequently settled with SynQor and are no longer parties to the Texas Action. With respect to the Company, SynQor’s complaint in the Texas Action alleged that the Company’s products, including but not limited to unregulated bus converters used in intermediate bus architecture power supply systems, infringe SynQor’s U.S. patent numbers 7,072,190, 7,272,021, and 7,564,702 (“the ‘190 patent”, “the ‘021 patent” and “the ‘702 patent”, respectively). SynQor’s complaint sought an injunction against further infringement and an award of unspecified compensatory and enhanced damages, interest, costs and attorney fees. On September 20, 2011, SynQor filed an amended complaint in the Texas Action that further alleged that the Company’s products, including, but not limited to, unregulated bus converters used in intermediate bus architecture power supply systems, infringe SynQor’s U.S. patent number 8,023,290 (“the ‘290 patent”). The Company responded to SynQor’s amended complaint in the Texas Action by denying its products infringe any of the SynQor patents, and asserting that the SynQor patents are invalid. The Company further alleged that the SynQor ‘290 patent is unenforceable due to inequitable conduct by SynQor or its agents during the examination of the ‘290 patent at the United States Patent and Trademark Office (“USPTO”). The Company also asserted counterclaims seeking damages against SynQor for deceptive trade practices and tortious interference with prospective economic advantage arising from SynQor’s attempted enforcement of its patents against the Company. The Company initiated administrative review proceedings at the USPTO challenging the validity of certain claims of the SynQor patents asserted in the Texas Action, including all claims that were asserted against the Company by SynQor. Regarding the ‘190 patent, the Patent Trial and Appeal Board (“PTAB”) of the USPTO issued a decision upholding the validity of the ‘190 patent claims. That decision was appealed by the Company to the United States Court of Appeals for the Federal Circuit (“the Federal Circuit”), which issued a decision on March 13, 2015 reversing the PTAB, determining that certain claims were invalid, and remanding the matter to the PTAB for further proceedings. On May 2, 2016, the PTAB issued a decision determining that all but one of the remaining claims of the ‘190 patent were invalid and remanding the remaining claim to a patent examiner for further examination. On June 22, 2017, the examiner issued a determination under 37 C.F.R. § 41.77(d), finding that the remaining claim of the ‘190 patent was unpatentable. That decision is expected to be further reviewed by the PTAB pursuant to 37 C.F.R. § 41.77(f). On May 2, 2016, the PTAB also issued decisions finding all challenged claims of SynQor’s ‘021 patent invalid and upholding the validity of all challenged claims of SynQor’s ‘702 and ‘290 patents. On May 23, 2016, the Texas Court issued an order staying the Texas Action until the completion of all of the administrative review proceedings concerning the asserted SynQor patents, including any appeals from such proceedings to the Federal Circuit. On August 30, 2017, the Federal Circuit issued rulings with regard to PTAB’s reexamination decisions for the ‘021, ‘702 and ‘290 patents. With respect to the ‘021 patent, the Federal Circuit affirmed the PTAB’s determination that all of the challenged claims of the ‘021 patent were invalid. The Federal Circuit remanded the case to the PTAB for further consideration of the patentability of certain claims that had been added by amendment during the reexamination. With respect to the ‘702 patent, the Federal Circuit affirmed the PTAB’s determination that all of the challenged claims of the ‘702 patent were patentable. With respect to the ‘290 patent, the Federal Circuit vacated the PTAB’s decision upholding the patentability of the ‘290 patent claims, and remanded the case to the PTAB for further consideration. The Company continues to believe none of its products, including its unregulated bus converters, infringe any valid claim of the asserted SynQor patents, either alone or when used in an intermediate bus architecture implementation. The Company believes SynQor’s claims lack merit and, therefore, continues to vigorously defend itself against SynQor’s patent infringement allegations. The Company does not believe a loss is probable for this matter. If a loss were to be incurred, however, the Company cannot estimate the amount of possible loss or range of possible loss at this time. In addition to the SynQor matter, the Company is involved in certain other litigation and claims incidental to the conduct of its business. While the outcome of lawsuits and claims against the Company cannot be predicted with certainty, management does not expect any current litigation or claims will have a material adverse impact on the Company’s financial position or results of operations.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Information	10. Segment Information The Company has organized its business segments according to its key product lines. The Brick Business Unit segment (“BBU”) designs, develops, manufactures and markets the Company’s modular DC-DC The Company’s chief operating decision maker evaluates performance and allocates resources based on segment revenues and segment operating income (loss). The operating income (loss) for each segment includes selling, general and administrative and research and development expenses directly attributable to the segment. Certain of the Company’s indirect overhead costs, which include corporate selling, general and administrative expenses, are allocated among the segments based upon an estimate of costs associated with each segment. Assets allocated to each segment are based upon specific identification of such assets, which include accounts receivable, inventories, fixed assets and certain other assets. The Corporate segment consists of those operations and assets shared by all segments. The costs of certain centralized executive and administrative functions are recorded in this segment, as are certain shared assets, most notably cash and cash equivalents, deferred tax assets, long-term investments, the Company’s facilities in Massachusetts, real estate and other assets. The Company’s accounting policies and method of presentation for segments are consistent with that used throughout the Condensed Consolidated Financial Statements. The following table provides segment financial data for the three months ended September 30 (in thousands): BBU VI Chip Picor Corporate Eliminations Total 2017: Net revenues $ 38,529 $ 14,745 $ 6,360 $ — $ (2,746 ) $ 56,888 Income (loss) from operations 2,007 (2,952 ) 1,359 (314 ) — 100 Total assets 227,408 33,021 11,934 64,864 (171,151 ) 166,076 Depreciation and amortization 971 712 188 373 — 2,244 2016: Net revenues $ 38,518 $ 11,961 $ 5,320 $ — $ (2,572 ) $ 53,227 Income (loss) from operations 3,734 (1,915 ) 627 (173 ) — 2,273 Total assets 193,115 21,453 6,928 72,521 (138,979 ) 155,038 Depreciation and amortization 1,025 531 142 375 — 2,073 The following table provides segment financial data for the nine months ended September 30 (in thousands): BBU VI Chip Picor Corporate Eliminations Total 2017: Net revenues $ 115,141 $ 42,835 $ 19,553 $ — $ (8,470 ) $ 169,059 Income (loss) from operations 5,962 (10,761 ) 3,825 (842 ) — (1,816 ) Total assets 227,408 33,021 11,934 64,864 (171,151 ) 166,076 Depreciation and amortization 2,944 2,000 558 1,088 — 6,590 2016: Net revenues $ 115,963 $ 30,126 $ 12,596 $ — $ (6,490 ) $ 152,195 Income (loss) from operations 9,475 (12,131 ) (510 ) (591 ) — (3,757 ) Total assets 193,115 21,453 6,928 72,521 (138,979 ) 155,038 Depreciation and amortization 3,293 1,660 404 1,027 — 6,384 (1) The elimination for net revenues is principally related to inter-segment sales by Picor to BBU and VI Chip and for inter-segment sales by VI Chip to BBU. The elimination for total assets is principally related to inter-segment accounts receivable due to BBU for the funding of VI Chip and Picor operations.

Impact of Recently Issued Accou

Impact of Recently Issued Accounting Standards	9 Months Ended
	Sep. 30, 2017
Accounting Changes and Error Corrections [Abstract]
Impact of Recently Issued Accounting Standards	11. Impact of Recently Issued Accounting Standards In May 2017, the Financial Accounting Standards Board (“FASB”) issued guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718, Compensation – Stock Compensation In August 2016, the FASB issued guidance to clarify how certain cash receipts and cash payments should be presented in the statement of cash flows. These include debt prepayment, settlement of zero-coupon In June 2016, the FASB issued new guidance which will require measurement and recognition of expected credit losses on certain types of financial instruments. It also modifies the impairment model for available-for-sale In March 2016, the FASB issued new guidance for employee share-based payment accounting, which makes several modifications to existing guidance related to the accounting for forfeitures, employer tax withholding on share-based compensation and the financial statement presentation of excess tax benefits or deficiencies. This new guidance also clarifies the statement of cash flows presentation for certain components of share-based awards. In terms of the accounting for forfeitures, the new guidance allows an option for them to either be estimated, as currently required, or recognized when they occur. The Company will continue to estimate forfeitures. The Company adopted the new standard on January 1, 2017. (See Note 8 – Income Taxes for additional details on the impact of the adoption). In February 2016, the FASB issued new guidance for lease accounting, which will require lessees to recognize leases on the balance sheet and disclose key information about leasing arrangements. The new guidance establishes a right-of-use In May 2014, the FASB issued new guidance for revenue recognition, which will require an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The new guidance, which includes several amendments, will replace most existing revenue recognition guidance in U.S. Generally Accepted Accounting Principles when it becomes effective, which will be January 1, 2018 for the Company. The new standard permits the use of either the retrospective or cumulative effect transition method. The Company has established an implementation team to assess the potential impact of the new standard which includes identifying appropriate changes to the business processes, systems and controls to support revenue recognition and disclosure requirements under the new standard. While the implementation team is still in the process of completing its evaluation of the new standard, it has reached preliminary conclusions on substantially all key accounting assessments, and currently believes the most significant impact will be related to the timing of recognition of sales to its stocking distributors. The Company currently defers revenue and the related cost of sales on shipments to stocking distributors until the distributors resell the products to their customers. Upon adoption of the new guidance, the Company will no longer be permitted to defer revenue until sale by the stocking distributor to the end customer, but rather, will be required to estimate the effects of returns and allowances provided to stocking distributors and record revenue at the time of sale to the stocking distributor. The Company currently plans to utilize the retrospective transition method for adoption of the standard. Upon adoption under that method, the Company will recognize the cumulative effect of adopting this guidance as an adjustment to the balance of retained earnings as of January 1, 2016. The implementation team is continuing to evaluate the method of adoption and the future impact the new guidance will have on its consolidated financial statements and related disclosures and expects to complete its assessment of those financial statement impacts during the fourth quarter of 2017. The other principal remaining implementation items include completing the identification and documentation of key transition controls and, later, the identification and documentation of any new or revised key ongoing process controls. The implementation team expects to complete those tasks by the end of the fourth quarter of 2017. The implementation team has reported its findings and status to the Audit Committee on a regular basis over the last year. Other new pronouncements issued but not effective until after September 30, 2017 are not expected to have a material impact on the Company’s consolidated financial statements.

Impact of Recently Issued Acc19

Impact of Recently Issued Accounting Standards (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Changes and Error Corrections [Abstract]
Impact of Recently Issued Accounting Standards	In May 2017, the Financial Accounting Standards Board (“FASB”) issued guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718, Compensation – Stock Compensation In August 2016, the FASB issued guidance to clarify how certain cash receipts and cash payments should be presented in the statement of cash flows. These include debt prepayment, settlement of zero-coupon In June 2016, the FASB issued new guidance which will require measurement and recognition of expected credit losses on certain types of financial instruments. It also modifies the impairment model for available-for-sale In March 2016, the FASB issued new guidance for employee share-based payment accounting, which makes several modifications to existing guidance related to the accounting for forfeitures, employer tax withholding on share-based compensation and the financial statement presentation of excess tax benefits or deficiencies. This new guidance also clarifies the statement of cash flows presentation for certain components of share-based awards. In terms of the accounting for forfeitures, the new guidance allows an option for them to either be estimated, as currently required, or recognized when they occur. The Company will continue to estimate forfeitures. The Company adopted the new standard on January 1, 2017. (See Note 8 – Income Taxes for additional details on the impact of the adoption). In February 2016, the FASB issued new guidance for lease accounting, which will require lessees to recognize leases on the balance sheet and disclose key information about leasing arrangements. The new guidance establishes a right-of-use In May 2014, the FASB issued new guidance for revenue recognition, which will require an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The new guidance, which includes several amendments, will replace most existing revenue recognition guidance in U.S. Generally Accepted Accounting Principles when it becomes effective, which will be January 1, 2018 for the Company. The new standard permits the use of either the retrospective or cumulative effect transition method. The Company has established an implementation team to assess the potential impact of the new standard which includes identifying appropriate changes to the business processes, systems and controls to support revenue recognition and disclosure requirements under the new standard. While the implementation team is still in the process of completing its evaluation of the new standard, it has reached preliminary conclusions on substantially all key accounting assessments, and currently believes the most significant impact will be related to the timing of recognition of sales to its stocking distributors. The Company currently defers revenue and the related cost of sales on shipments to stocking distributors until the distributors resell the products to their customers. Upon adoption of the new guidance, the Company will no longer be permitted to defer revenue until sale by the stocking distributor to the end customer, but rather, will be required to estimate the effects of returns and allowances provided to stocking distributors and record revenue at the time of sale to the stocking distributor. The Company currently plans to utilize the retrospective transition method for adoption of the standard. Upon adoption under that method, the Company will recognize the cumulative effect of adopting this guidance as an adjustment to the balance of retained earnings as of January 1, 2016. The implementation team is continuing to evaluate the method of adoption and the future impact the new guidance will have on its consolidated financial statements and related disclosures and expects to complete its assessment of those financial statement impacts during the fourth quarter of 2017. The other principal remaining implementation items include completing the identification and documentation of key transition controls and, later, the identification and documentation of any new or revised key ongoing process controls. The implementation team expects to complete those tasks by the end of the fourth quarter of 2017. The implementation team has reported its findings and status to the Audit Committee on a regular basis over the last year. Other new pronouncements issued but not effective until after September 30, 2017 are not expected to have a material impact on the Company’s consolidated financial statements.

Long-Term Investments (Tables)

Long-Term Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Securities	The following is a summary of available-for-sale September 30, 2017 Cost Gross Gross Estimated Failed Auction Security $ 3,000 $ — $ 401 $ 2,599 December 31, 2016 Cost Gross Gross Estimated Failed Auction Security $ 3,000 $ — $ 492 $ 2,508
Rollforward of Credit (Gain) Loss Recognized in Earnings on Failed Auction Security	The following table represents a rollforward of the activity related to the credit loss recognized in earnings on the Failed Auction Security for the nine months ended September 30 (in thousands): 2017 2016 Balance at the beginning of the period $ 59 $ 72 Reductions in the amount related to credit gain for which other-than-temporary impairment was not previously recognized (9 ) (10 ) Balance at the end of the period $ 50 $ 62

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis included the following as of September 30, 2017 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 9,258 $ — $ — $ 9,258 Long-term investments: Failed Auction Security — — 2,599 2,599 Liabilities: Contingent consideration obligations — — (78 ) (78 ) Assets and liabilities measured at fair value on a recurring basis included the following as of December 31, 2016 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 10,114 $ — $ — $ 10,114 Long-term investments: Failed Auction Security — — 2,508 2,508 Liabilities: Contingent consideration obligations — — (253 ) (253 )
Quantitative Information about Level 3 Fair Value Measurements	Quantitative information about Level 3 fair value measurements as of September 30, 2017 is as follows (dollars in thousands): Fair Valuation Unobservable Input Weighted Failed Auction Security $ 2,599 Discounted cash flow Cumulative probability of earning the maximum rate until maturity 0.04 % Cumulative probability of principal return prior to maturity 94.81 % Cumulative probability of default 5.15 % Liquidity risk premium 5.00 % Recovery rate in default 40.00 %
Change in Estimated Fair Values Calculated for Investment Valued on Recurring Basis Utilizing Level 3 Inputs	The change in the estimated fair value calculated for the investment valued on a recurring basis utilizing Level 3 inputs (i.e., the Failed Auction Security) for the nine months ended September 30, 2017 was as follows (in thousands): Balance at the beginning of the period $ 2,508 Credit gain on available-for-sale 9 Gain included in Other comprehensive income 82 Balance at the end of the period $ 2,599
Change in Estimated Fair Value Calculated for Liabilities Valued on Recurring Basis Utilizing Level 3 Inputs	The change in the estimated fair value calculated for the liabilities valued on a recurring basis utilizing Level 3 inputs (i.e., the Contingent consideration obligations) for the nine months ended September 30, 2017 was as follows (in thousands): Balance at the beginning of the period $ 253 Payments (175 ) Balance at the end of the period $ 78

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Expense	Stock-based compensation expense, net for the three and nine months ended September 30 was as follows (in thousands): Three Months Ended Nine Months Ended 2017 2016 2017 2016 Cost of revenues $ 53 $ (47 ) $ 125 $ 59 Selling, general and administrative 466 (327 ) 861 148 Research and development 212 (124 ) 286 (36 ) Total stock-based compensation $ 731 $ (498 ) $ 1,272 $ 171
Summary of Compensation Expense by Type of Award	Compensation expense by type of award for the three and nine months ended September 30, was as follows (in thousands): Three Months Ended Nine Months Ended 2017 2016 2017 2016 Stock options $ 689 $ (498 ) $ 1,230 $ 171 ESPP 42 — 42 — Total stock-based compensation $ 731 $ (498 ) $ 1,272 $ 171

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Computation Of Basic And Diluted Net Income (Loss) Per Share	The following table sets forth the computation of basic and diluted net income (loss) per share for the three and nine months ended September 30 (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Numerator: Net income (loss) attributable to Vicor Corporation $ (11 ) $ 2,336 $ (1,444 ) $ (3,559 ) Denominator: Denominator for basic net income (loss) per share-weighted average shares (1) 39,288 38,837 39,177 38,811 Effect of dilutive securities: Employee stock options (2) — 347 — — Denominator for diluted net income (loss) per share – adjusted weighted-average shares and assumed conversions 39,288 39,184 39,177 38,811 Basic net income (loss) per share $ (0.00 ) $ 0.06 $ (0.04 ) $ (0.09 ) Diluted net income (loss) per share $ (0.00 ) $ 0.06 $ (0.04 ) $ (0.09 ) (1) Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding. (2) Options to purchase 1,452,808 shares of Common Stock for the three and nine months ended September 30, 2017 were not included in the calculation of net loss per share as the effect would have been antidilutive. Options to purchase 449,464 and 1,845,289 shares of Common Stock for the three and nine months ended September 30, 2016, respectively, were not included in the calculation of net income (loss) per share as the effect would have been antidilutive.

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories were as follows (in thousands): September 30, 2017 December 31, 2016 Raw materials $ 26,247 $ 18,648 Work-in-process 2,774 3,361 Finished goods 4,862 5,127 Net balance $ 33,883 $ 27,136

Product Warranties (Tables)

Product Warranties (Tables)	9 Months Ended
	Sep. 30, 2017
Guarantees and Product Warranties [Abstract]
Product Warranty Activity	Product warranty activity for the three and nine months ended September 30 was as follows (in thousands): Three Months Ended Nine Months Ended 2017 2016 2017 2016 Balance at the beginning of the period $ 244 $ 496 $ 214 $ 584 Accruals for warranties for products sold in the period 126 61 321 291 Fulfillment of warranty obligations (82 ) (106 ) (179 ) (374 ) Revisions of estimated obligations — (109 ) (68 ) (159 ) Balance at the end of the period $ 288 $ 342 $ 288 $ 342

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Provision for Income Taxes and Effective Income Tax Rates	The provision for income taxes and the effective income tax rates for the three and nine months ended September 30 were as follows (dollars in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2017 2016 2017 2016 Provision for income taxes $ 371 $ 133 $ 539 $ 168 Effective income tax rate 90.7 % 5.4 % 65.6 % 4.9 %

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Financial Data	The following table provides segment financial data for the three months ended September 30 (in thousands): BBU VI Chip Picor Corporate Eliminations Total 2017: Net revenues $ 38,529 $ 14,745 $ 6,360 $ — $ (2,746 ) $ 56,888 Income (loss) from operations 2,007 (2,952 ) 1,359 (314 ) — 100 Total assets 227,408 33,021 11,934 64,864 (171,151 ) 166,076 Depreciation and amortization 971 712 188 373 — 2,244 2016: Net revenues $ 38,518 $ 11,961 $ 5,320 $ — $ (2,572 ) $ 53,227 Income (loss) from operations 3,734 (1,915 ) 627 (173 ) — 2,273 Total assets 193,115 21,453 6,928 72,521 (138,979 ) 155,038 Depreciation and amortization 1,025 531 142 375 — 2,073 The following table provides segment financial data for the nine months ended September 30 (in thousands): BBU VI Chip Picor Corporate Eliminations Total 2017: Net revenues $ 115,141 $ 42,835 $ 19,553 $ — $ (8,470 ) $ 169,059 Income (loss) from operations 5,962 (10,761 ) 3,825 (842 ) — (1,816 ) Total assets 227,408 33,021 11,934 64,864 (171,151 ) 166,076 Depreciation and amortization 2,944 2,000 558 1,088 — 6,590 2016: Net revenues $ 115,963 $ 30,126 $ 12,596 $ — $ (6,490 ) $ 152,195 Income (loss) from operations 9,475 (12,131 ) (510 ) (591 ) — (3,757 ) Total assets 193,115 21,453 6,928 72,521 (138,979 ) 155,038 Depreciation and amortization 3,293 1,660 404 1,027 — 6,384 (1) The elimination for net revenues is principally related to inter-segment sales by Picor to BBU and VI Chip and for inter-segment sales by VI Chip to BBU. The elimination for total assets is principally related to inter-segment accounts receivable due to BBU for the funding of VI Chip and Picor operations.

Long-Term Investments - Additio

Long-Term Investments - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Unrealized Losses On Short Term And Long Term Investments [Line Items]
Minimum period for which failed auction securities been in unrealized loss position	12 months
Failed Auction Security [Member]
Unrealized Losses On Short Term And Long Term Investments [Line Items]
Amortized cost of securities	$ 3,000,000	$ 3,000,000
Period for which failed auction securities been in unrealized loss position	Exceeds 12 months
Estimated Fair Value	$ 2,599,000	2,508,000
Gross Unrealized Losses	401,000	492,000
Aggregate credit loss	50,000	$ 59,000	$ 62,000	$ 72,000
Aggregate temporary impairment loss	$ 351,000

Long-Term Investments - Summary

Long-Term Investments - Summary of Available-for-Sale Securities (Detail) - Failed Auction Security [Member] - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 3,000,000	$ 3,000,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	401,000	492,000
Estimated Fair Value	$ 2,599,000	$ 2,508,000

Long-Term Investments - Rollfor

Long-Term Investments - Rollforward of Credit (Gain) Loss Recognized in Earnings on Failed Auction Security (Detail) - Failed Auction Security [Member] - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Balance at the beginning of the period	$ 59,000	$ 72,000
Reductions in the amount related to credit gain for which other-than-temporary impairment was not previously recognized	(9,000)	(10,000)
Balance at the end of the period	$ 50,000	$ 62,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Failed Auction Security [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	$ 2,599,000	$ 2,508,000
Recurring [Member] | Contingent Consideration Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liabilities, fair value on recurring basis	(78,000)	(253,000)
Recurring [Member] | Failed Auction Security [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	2,599,000	2,508,000
Recurring [Member] | Money Market Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	9,258,000	10,114,000
Recurring [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Money Market Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	9,258,000	10,114,000
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Contingent Consideration Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liabilities, fair value on recurring basis	(78,000)	(253,000)
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Failed Auction Security [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	$ 2,599,000	$ 2,508,000

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017USD ($)
Fair Value Disclosures [Abstract]
Percent of credit loss	2.00%
Rate of return required	5.00%
Estimated timeframe for auctions of securities minimum	3 years
Estimated timeframe for auctions of securities maximum	5 years
Percentage of liquidity risk premium	5.00%
Increase or decrease in the liquidity risk premium	1.00%
Increase or decrease, respectively, the fair value of the Failed Auction Securities	$ 100,000
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Information about Level 3 Fair Value Measurements (Detail) - Failed Auction Security [Member] - Significant Unobservable Inputs (Level 3) [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$ 2,599
Valuation Technique	Discounted cash flow
Cumulative Probability of Earning Maximum Rate Until Maturity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable Input	Cumulative probability of earning the maximum rate until maturity
Weighted Average Interest Rate	0.04%
Cumulative Probability of Principal Return Prior to Maturity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable Input	Cumulative probability of principal return prior to maturity
Weighted Average Interest Rate	94.81%
Cumulative Probability of Default [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable Input	Cumulative probability of default
Weighted Average Interest Rate	5.15%
Liquidity Risk Premium [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable Input	Liquidity risk premium
Weighted Average Interest Rate	5.00%
Recovery Rate in Default [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable Input	Recovery rate in default
Weighted Average Interest Rate	40.00%

Fair Value Measurements - Chang

Fair Value Measurements - Change in Estimated Fair Values Calculated for Investment Valued on Recurring Basis Utilizing Level 3 Inputs (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Fair Value Disclosures [Abstract]
Balance at the beginning of the period	$ 2,508
Credit gain on available-for-sale securities included in Other income (expense), net	9
Gain included in Other comprehensive income	82
Balance at the end of the period	$ 2,599

Fair Value Measurements - Cha35

Fair Value Measurements - Change in Estimated Fair Value Calculated for Liabilities Valued on Recurring Basis Utilizing Level 3 Inputs (Detail) - Significant Unobservable Inputs (Level 3) [Member] - Contingent Consideration Obligations [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at the beginning of the period	$ 253
Payments	(175)
Balance at the end of the period	$ 78

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2010
2017 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares authorized for issuances		2,000,000
Price of common stock purchased under ESPP, percent		85.00%
Maximum percentage of payroll deductions on employee's compensation		15.00%
Offering period of employee stock purchase plan		6 months
2007 VI Chip Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-qualified stock options				2,984,250
Stock-based compensation expense reversed	$ 768,000
2007 VI Chip Plan [Member] | Cost of Revenues [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Decrease in costs and expenses due to reversal of share-based compensation expense	86,000		$ 86,000
2007 VI Chip Plan [Member] | Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Decrease in costs and expenses due to reversal of share-based compensation expense	516,000		516,000
2007 VI Chip Plan [Member] | Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Decrease in costs and expenses due to reversal of share-based compensation expense	$ 166,000		$ 166,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 731	$ (498)	$ 1,272	$ 171
Cost of Revenues [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	53	(47)	125	59
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	466	(327)	861	148
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 212	$ (124)	$ 286	$ (36)

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Compensation Expense by Type of Award (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 731	$ (498)	$ 1,272	$ 171
Stock Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	689	$ (498)	1,230	$ 171
ESPP [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 42		$ 42

Net Income (Loss) per Share - C

Net Income (Loss) per Share - Computation Of Basic And Diluted Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net income (loss) attributable to Vicor Corporation	$ (11)	$ 2,336	$ (1,444)	$ (3,559)
Denominator:
Denominator for basic net income (loss) per share-weighted average shares	39,288	38,837	39,177	38,811
Effect of dilutive securities:
Employee stock options		347
Denominator for diluted net income (loss) per share - adjusted weighted-average shares and assumed conversions	39,288	39,184	39,177	38,811
Basic net income (loss) per share	$ 0	$ 0.06	$ (0.04)	$ (0.09)
Diluted net income (loss) per share	$ 0	$ 0.06	$ (0.04)	$ (0.09)

Net Income (Loss) per Share -40

Net Income (Loss) per Share - Computation Of Basic And Diluted Net Income (Loss) Per Share (Parenthetical) (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Options to purchase shares of Common Stock not included in the calculation of net income (loss) per share	1,452,808	449,464	1,452,808	1,845,289

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 26,247	$ 18,648
Work-in-process	2,774	3,361
Finished goods	4,862	5,127
Net balance	$ 33,883	$ 27,136

Product Warranties - Additional

Product Warranties - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017
Guarantees [Abstract]
Product warranty period	2 years
Extended product warranty period	3 years
Extended product warranty description	Effective January 1, 2017, the Company extended the warranty period to three years for certain military grade products sold after that date.

Product Warranties - Product Wa

Product Warranties - Product Warranty Activity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Guarantees [Abstract]
Balance at the beginning of the period	$ 244	$ 496	$ 214	$ 584
Accruals for warranties for products sold in the period	126	61	321	291
Fulfillment of warranty obligations	(82)	(106)	(179)	(374)
Revisions of estimated obligations		(109)	(68)	(159)
Balance at the end of the period	$ 288	$ 342	$ 288	$ 342

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes and Effective Income Tax Rates (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 371	$ 133	$ 539	$ 168
Effective income tax rate	90.70%	5.40%	65.60%	4.90%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 0	$ 0	$ 0	$ 0
Tax benefit recognized	0	$ 0	0	$ 0
Cumulative-effect adjustment to increase gross deferred tax assets and related valuation allowance against deferred tax assets	3,485,000		3,485,000
Valuation allowance, deferred tax assets	$ 32,746,000		$ 32,746,000
Converpower Corporation [Member]
Income Tax Disclosure [Line Items]
Ownership percentage by parent in certain operating assets and cash	100.00%		100.00%
Unremitted earnings reversed			$ 55,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Sep. 30, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Capital expenditure commitments	$ 3,006,000

Segment Information - Segment F

Segment Information - Segment Financial Data (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net revenues	$ 56,888	$ 53,227	$ 169,059	$ 152,195
Income (loss) from operations	100	2,273	(1,816)	(3,757)
Total assets	166,076	155,038	166,076	155,038	$ 154,067
Depreciation and amortization	2,244	2,073	6,590	6,384
Operating Segments [Member] | BBU [Member]
Segment Reporting Information [Line Items]
Net revenues	38,529	38,518	115,141	115,963
Income (loss) from operations	2,007	3,734	5,962	9,475
Total assets	227,408	193,115	227,408	193,115
Depreciation and amortization	971	1,025	2,944	3,293
Operating Segments [Member] | VI Chip [Member]
Segment Reporting Information [Line Items]
Net revenues	14,745	11,961	42,835	30,126
Income (loss) from operations	(2,952)	(1,915)	(10,761)	(12,131)
Total assets	33,021	21,453	33,021	21,453
Depreciation and amortization	712	531	2,000	1,660
Operating Segments [Member] | Picor [Member]
Segment Reporting Information [Line Items]
Net revenues	6,360	5,320	19,553	12,596
Income (loss) from operations	1,359	627	3,825	(510)
Total assets	11,934	6,928	11,934	6,928
Depreciation and amortization	188	142	558	404
Operating Segments [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(314)	(173)	(842)	(591)
Total assets	64,864	72,521	64,864	72,521
Depreciation and amortization	373	375	1,088	1,027
Eliminations [Member]
Segment Reporting Information [Line Items]
Net revenues	(2,746)	(2,572)	(8,470)	(6,490)
Total assets	$ (171,151)	$ (138,979)	$ (171,151)	$ (138,979)