Vicor (VICR) 10-Q 30 Apr 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 24, 2015
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	VICR
Entity Registrant Name	VICOR CORP
Entity Central Index Key	751978
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		26,978,949
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 $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$59,322	$55,187
Short-term investments	90	270
Accounts receivable, less allowance of $215 in 2015 and $183 in 2014	32,675	28,431
Inventories, net	24,837	26,328
Deferred tax assets	107	107
Other current assets	3,180	3,155
Total current assets	120,211	113,478
Long-term investments, net	2,902	3,002
Property, plant and equipment, net	36,460	37,387
Other assets	1,700	1,675
Total assets	161,273	155,542
Current liabilities:
Accounts payable	10,111	7,932
Accrued compensation and benefits	9,172	8,663
Accrued expenses	2,217	3,178
Accrued severance charges	1,313	1,904
Income taxes payable	17	41
Deferred revenue	1,854	1,439
Total current liabilities	24,684	23,157
Long-term deferred revenue	572	637
Long-term income taxes payable	873	867
Deferred income taxes payable	329	329
Total liabilities	26,458	24,990
Commitments and contingencies (Note 11)
Vicor Corporation stockholders' equity:
Common Stock	393	393
Additional paid-in capital	172,774	171,901
Retained earnings	98,129	94,758
Accumulated other comprehensive loss	-523	-471
Treasury stock, at cost	-138,927	-138,927
Total Vicor Corporation stockholders' equity	131,964	127,772
Noncontrolling interest	2,851	2,780
Total equity	134,815	130,552
Total liabilities and equity	161,273	155,542
Class B Common Stock [Member]
Vicor Corporation stockholders' equity:
Common Stock	$118	$118

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$215	$183

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Net revenues	$64,017	$53,233
Cost of revenues	35,126	30,441
Gross margin	28,891	22,792
Operating expenses:
Selling, general and administrative	14,862	17,980
Research and development	10,419	10,251
Total operating expenses	25,281	28,231
Income (loss) from operations	3,610	-5,439
Other income (expense), net:
Total unrealized (losses) gains on available-for-sale securities, net	-15	39
Portion of losses (gains) recognized in other comprehensive income (loss)	19	-39
Net credit gains recognized in earnings	4
Other income (expense), net	-33	30
Total other income (expense), net	-29	30
Income (loss) before income taxes	3,581	-5,409
Provision for income taxes	139	17
Consolidated net income (loss)	3,442	-5,426
Less: Net income (loss) attributable to noncontrolling interest	71	-48
Net income (loss) attributable to Vicor Corporation	$3,371	($5,378)
Net income (loss) per common share attributable to Vicor Corporation:
Basic	$0.09	($0.14)
Diluted	$0.09	($0.14)
Shares used to compute net income (loss) per common share attributable to Vicor Corporation:
Basic	38,689	38,541
Diluted	39,149	38,541

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Consolidated net income (loss)	$3,442		($5,426)
Foreign currency translation (losses) gains, net of tax	-37	[1]	77	[1]
Unrealized (losses) gains on available-for-sale securities, net of tax	-15	[2]	37	[2]
Other comprehensive income (loss)	-52		114
Consolidated comprehensive income (loss)	3,390		-5,312
Less: Comprehensive income (loss) attributable to noncontrolling interest	71		-43
Comprehensive income (loss) attributable to Vicor Corporation	$3,319		($5,269)
[1]	Net of tax benefit of $0 for the three months ended March 31, 2015 and 2014, respectively.
[2]	The deferred tax assets associated with cumulative unrealized losses on available-for-sale securities are completely offset by a tax valuation allowance as of March 31, 2015 and 2014. Therefore, there is no net income tax benefit recognized for the three months ended March 31, 2015 and 2014.

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Foreign currency translation gains (losses), tax benefit	$0	$0
Recognized income tax provision (benefit)	$0	$0

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Consolidated net income (loss)	$3,442	($5,426)
Adjustments to reconcile consolidated net income (loss) to net cash provided by (used for) operating activities:
Depreciation and amortization	2,403	2,443
Stock-based compensation expense	563	234
Provision for doubtful accounts	33	53
Decrease in long-term deferred revenue	-34	-34
Gain on disposal of equipment	-35	-4
Credit gain on available-for-sale securities	-4
Increase (decrease) in long-term income taxes payable	6	-2
Change in current assets and liabilities, net	-1,304	-1,744
Net cash provided by (used for) operating activities	5,070	-4,480
Investing activities:
Additions to property, plant and equipment	-1,469	-1,554
Sales and maturities of investments	270
Proceeds from sale of equipment	35	4
Increase in other assets	-65	-34
Net cash used for investing activities	-1,229	-1,584
Financing activities:
Proceeds from issuance of Common Stock	310	5
Net cash provided by financing activities	310	5
Effect of foreign exchange rates on cash	-16	27
Net increase (decrease) in cash and cash equivalents	4,135	-6,032
Cash and cash equivalents at beginning of period	55,187	56,339
Cash and cash equivalents at end of period	$59,322	$50,307

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	1	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements of Vicor Corporation and its consolidated subsidiaries (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 months ended March 31, 2015 are not necessarily indicative of the results that may be expected for any other interim period or the year ending December 31, 2015. The balance sheet at December 31, 2014 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 for the year ended December 31, 2014 (File No. 0-18277) filed by the Company with the Securities and Exchange Commission.

ShortTerm_and_LongTerm_Investm

Short-Term and Long-Term Investments	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Short-Term and Long-Term Investments	2	Short-Term and Long-Term Investments
	As of March 31, 2015 and December 31, 2014, the Company held one auction rate security that had experienced failed auctions totaling $3,000,000 at par value, which was purchased through and is held by a broker-dealer affiliate of Bank of America, N.A. (the “Failed Auction Security”). The Failed Auction Security held by the Company is Aaa/AA+ rated by major credit rating agencies, collateralized by student loans, and 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 March 31, 2015, 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 March 31, 2015.
	The following is a summary of available-for-sale securities (in thousands):
	31-Mar-15		Cost			Gross		Gross		Estimated
						Unrealized		Unrealized		Fair
						Gains		Losses		Value
	Failed Auction Security		$	3,000		$	—	$	440	$	2,560
	Brokered certificates of deposit			430			2				432
			$	3,430		$	2	$	440	$	2,992
	December 31, 2014		Cost			Gross		Gross		Estimated
						Unrealized		Unrealized		Fair
						Gains		Losses		Value
	Failed Auction Security		$	3,000		$	—	$	425	$	2,575
	Brokered certificates of deposit			700			—		3		697
			$	3,700		$	—	$	428	$	3,272
	The Failed Auction Security as of March 31, 2015 has been in an unrealized loss position for greater than 12 months.
	The amortized cost and estimated fair value of available-for-sale securities on March 31, 2015, by contractual maturities, are shown below (in thousands):
			Cost			Estimated
						Fair Value
	Due in one year or less		$	90		$	90
	Due in two to ten years			340			342
	Due in ten to twenty years			—			—
	Due in twenty to forty years			3,000			2,560
			$	3,430		$	2,992
	Based on the fair value measurements described in Note 3, the fair value of the Failed Auction Security on March 31, 2015, with a par value of $3,000,000, was estimated by the Company to be approximately $2,560,000. The gross unrealized loss of $440,000 on the Failed Auction Security consists of two types of estimated loss: an aggregate credit loss of $80,000 and an aggregate temporary impairment of $360,000. 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 available-for-sale auction rate securities held by the Company for the three months ended March 31 (in thousands):
			2015			2014
	Balance at the beginning of the period		$	84		$	395
	Changes in the amount related to credit loss for which other-than- temporary impairment was not previously recognized			(4	)		—
	Balance at the end of the period		$	80		$	395
	A Failed Auction Security held as of December 31, 2013 was redeemed at par value of $3,000,000 during the fourth quarter of 2014.
	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 these investments 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	3 Months Ended
	Mar. 31, 2015
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 measured at fair value on a recurring basis include the following as of March 31, 2015 (in thousands):
			Using
			Quoted Prices			Significant			Significant			Total Fair
			in Active			Other			Unobservable			Value as of
			Markets			Observable			Inputs			March 31, 2015
			(Level 1)			Inputs			(Level 3)
						(Level 2)
	Cash equivalents:
	Money market funds		$	11,450		$	—		$	—		$	11,450
	Short-term investments:
	Brokered certificates of deposit			—			90			—			90
	Long-term investments:
	Failed Auction Security			—			—			2,560			2,560
	Brokered certificates of deposit			—			342			—			342
	Assets measured at fair value on a recurring basis include the following as of December 31, 2014 (in thousands):
			Using
			Quoted Prices			Significant			Significant			Total Fair
			in Active			Other			Unobservable			Value as of
			Markets			Observable			Inputs			December 31, 2014
			(Level 1)			Inputs			(Level 3)
						(Level 2)
	Cash equivalents:
	Money market funds		$	11,207		$	—		$	—		$	11,207
	Short-term investments:
	Brokered certificates of deposit			—			270			—			270
	Long-term investments:
	Failed Auction Security			—			—			2,575			2,575
	Brokered certificates of deposit			—			427			—			427
	The Company has brokered certificates of deposit classified as Level 2 because the fair value for these investments has been determined utilizing observable inputs from non-active markets. The fair values fluctuate with changes in market interest rates obtained from information available in publicly quoted markets. Management tested the reported fair values by comparing them to net present value calculations utilizing a discount rate based on U.S. Treasury bill and bond yields for similar maturities.
	As of March 31, 2015, 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 March 31, 2015. 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 2.7%; 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 Rates 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 arms’ 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.
	For purposes of the valuation process for the Failed Auction Security, “management” consists of senior members of the Company’s finance department. The fair value measurements for the Failed Auction Security are reviewed and updated on a quarterly basis. The calculations are prepared by the Company’s Corporate Controller, in conjunction with information provided by its valuation advisors, and include the development and substantiation of the unobservable inputs. The methodology, assumptions, and calculations are reviewed and approved by the Company’s Chief Financial Officer and Chief Accounting Officer.
	The significant unobservable inputs used in the fair value measurement of the Company’s 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 March 31, 2015 are as follows (dollars in thousands):
			Fair Value			Valuation		Unobservable	Weighted
						Technique			Average
								Input
	Failed Auction Security		$	2,560		Discounted		Cumulative probability of earning		0.02	%
						cash flow
								the maximum rate until maturity
								Cumulative probability of principal		94.07	%
								return prior to maturity
								Cumulative probability of default		5.91	%
								Liquidity risk premium		5	%
								Recovery rate in default		40	%
	The change in the estimated fair values calculated for those assets valued on a recurring basis utilizing Level 3 inputs (i.e., the Failed Auction Security) for the three months ended March 31, 2015 was as follows (in thousands):
	Balance at the beginning of the period		$	2,575
	Credit gain on available-for-sale securities included in Other income (expense), net			4
	Loss included in Other comprehensive income (loss)			(19	)
	Balance at the end of the period		$	2,560
	There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2015.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	4	Stock-Based Compensation
	The Company uses the Black-Scholes option pricing model to calculate the fair value of stock option awards as of their grant date. Stock-based compensation expense for the three months ended March 31 was as follows (in thousands):
			Three Months Ended
			March 31,
			2015		2014
	Cost of revenues		$	61	$	36
	Selling, general and administrative			408		191
	Research and development			94		7
	Total stock-based compensation		$	563	$	234
	The increase in selling, general and administrative stock-based compensation for the three months ended March 31, 2015 compared to the same period a year ago is primarily due to increased expense for certain Vicor stock options held by a non-employee. The fair value of these stock options, and related stock-based compensation, are adjusted monthly based on changes in the assumptions under the Black-Scholes option pricing model, including the price of the Company’s common stock, in accordance with the accounting for stock options granted to non-employees.
	On December 31, 2010, the Company granted 2,984,250 non-qualified stock options under the VI Chip 2007 Stock Option and Incentive Plan with performance-based vesting provisions tied to achievement of certain margin targets by the VI Chip subsidiary. As of December 31, 2010, the Company determined it was probable the margin targets could be achieved and, accordingly, began recording stock-based compensation expense relating to these options beginning January 1, 2011. This determination remains the same as of March 31, 2015 and, accordingly, expense has been recorded through that date. The unrecognized compensation expense for these performance-based options was approximately $570,000 as of March 31, 2015.

Net_Income_Loss_per_Share

Net Income (Loss) per Share	3 Months Ended
	Mar. 31, 2015
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 months ended March 31 (in thousands, except per share amounts):
			Three Months Ended
			March 31,
			2015		2014
	Numerator:
	Net income (loss) attributable to Vicor Corporation		$	3,371	$	(5,378	)
	Denominator:
	Denominator for basic net income (loss) per share-weighted average shares (1)			38,689		38,541
	Effect of dilutive securities:
	Employee stock options (2)			460		—
	Denominator for diluted net income (loss) per share – adjusted weighted-average shares and assumed conversions			39,149		38,541
	Basic net income (loss) per share		$	0.09	$	(0.14	)
	Diluted net income (loss) per share		$	0.09	$	(0.14	)
	-1	Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding.
	-2	Options to purchase 112,929 and 1,981,028 shares of Common Stock for the three months ended March 31, 2015 and 2014, respectively, were not included in the calculation of net loss per share as the effect would have been antidilutive.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Inventories	6	Inventories
	Inventories are valued at the lower of cost (determined using the first-in, first-out method) or net realizable value. Fixed production overhead is allocated to the inventory cost per unit based on the normal capacity of the production facilities. Abnormal production costs, including fixed cost variances from normal production capacity, if any, are charged to cost of revenues in the period incurred. All shipping and handling costs incurred in connection with the sale of products are included in cost of revenues.
	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):
			March 31, 2015		December 31, 2014
	Raw materials		$	17,322	$	18,252
	Work-in-process			3,405		3,339
	Finished goods			4,110		4,737
	Net balance		$	24,837	$	26,328

Other_Investments

Other Investments	3 Months Ended
	Mar. 31, 2015
Text Block [Abstract]
Other Investments	7	Other Investments
	The Company’s gross investment in non-voting convertible preferred stock of Great Wall Semiconductor Corporation (“GWS”) totaled $5,000,000 as of March 31, 2015 and December 31, 2014, giving the Company an approximately 27% ownership interest in GWS. GWS and its subsidiary design and sell semiconductors, conduct research and development activities, develop and license patents, and litigate against those who infringe upon its patented technologies. A director of the Company is the founder, Chairman of the Board, President and Chief Executive Officer (“CEO”), as well as the majority voting shareholder, of GWS. The Company and GWS are parties to an intellectual property cross-licensing agreement, a license agreement and two supply agreements under which the Company purchases certain components from GWS. Purchases from GWS totaled approximately $1,057,000 and $942,000 for the three months ended March 31, 2015, and 2014, respectively. The Company owed GWS approximately $325,000 and $170,000 as of March 31, 2015 and December 31, 2014, respectively.
	The Company accounts for its investment in GWS under the equity method of accounting. The Company has determined, while GWS is a variable interest entity, the Company is not the primary beneficiary. The key factors in the Company’s assessment were that the CEO of GWS has: (i) the power to direct the activities of GWS that most significantly impact its economic performance, and (ii) an obligation to absorb losses or the right to receive benefits from GWS, respectively, that could potentially be significant to GWS.
	The balance in the Company’s net investment in GWS was zero as of March 31, 2015 and December 31, 2014.

Severance_and_Other_Charges

Severance and Other Charges	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Severance and Other Charges	8	Severance and Other Charges
	In July 2014, the Company’s management authorized the consolidation of the manufacturing of Westcor division products, of the Brick Business Unit segment, by transferring those operations from Westcor’s Sunnyvale, California facility to the Company’s primary manufacturing facility in Andover, Massachusetts, by the end of 2014. As a result, the Company recorded a pre-tax charge of $2,207,000 in the second half of 2014, primarily for the cost of severance and other employee-related costs involving cash payments based on each employee’s respective length of service. The Company also incurred other costs related to the relocation of the manufacturing operations, primarily freight costs for the transfer of inventories and equipment, and employee travel expenses, of which approximately $303,000 was expensed in the second half of 2014. These charges were recorded as “Severance and other charges” in the Consolidated Statement of Operations. The related liability is presented as “Accrued severance charges” in the Condensed Consolidated Balance Sheets.
	A summary of the activity related to the accrued severance charges, is as follows (in thousands):
	Balance as of December 31, 2014		$	1,904
	Payments			(591	)
	Balance as of March 31, 2015		$	1,313

Product_Warranties

Product Warranties	3 Months Ended
	Mar. 31, 2015
Guarantees [Abstract]
Product Warranties	9	Product Warranties
	The Company generally offers a two-year warranty for all of its products. The Company provides for the estimated cost of product warranties at the time product revenue is recognized. Factors influencing the Company’s warranty reserves include the number of units sold, historical and anticipated rates of warranty returns, and the cost per return. The Company periodically assesses the adequacy of warranty reserves and adjusts the amounts as necessary. Warranty obligations are included in “Accrued expenses” in the accompanying Condensed Consolidated Balance Sheets.
	Product warranty activity for the three months ended March 31, was as follows (in thousands):
			2015			2014
	Balance at the beginning of the period		$	204		$	283
	Accruals for warranties for products sold in the period			15			24
	Fulfillment of warranty obligations			(32	)		(55	)
	Revisions of estimated obligations			—			(3	)
	Balance at the end of the period		$	187		$	249

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	10	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 income (loss) and estimated federal and state income taxes for certain noncontrolling interest subsidiaries that are not part of the Company’s consolidated income tax returns.
	The provision for income taxes and the effective income tax rate for the three months ended March 31, were as follows (in thousands):
			2015			2014
	Provision for income taxes		$	139		$	17
	Effective income tax rate			3.9	%		0.3	%
	The provision for the three months ended March 31, 2015 was primarily due to estimated federal and state taxes for one noncontrolling interest subsidiary, and for estimated state taxes for the Company. The provision for the three months ended March 31, 2014 was primarily due to state taxes. No tax benefit could be recognized for the majority of the Company’s losses in either period due to a full valuation allowance against all domestic deferred tax assets.
	As of March 31, 2015, the Company has a valuation allowance of approximately $25,776,000 primarily against all domestic net deferred tax assets, for which realization cannot be considered more likely than not at this time. Management assesses the need for the valuation allowance on a quarterly basis. In assessing the need for a valuation allowance, the Company considers all positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies, and past financial performance. In 2013, the Company recorded an increase to the valuation allowance of approximately $10,241,000 for all remaining domestic net deferred tax assets not previously covered by a valuation allowance due to the following factors: (1) the Company’s forecast of future taxable income, of the appropriate nature, based on its quarterly assessment was not sufficient to support the recoverability of the remaining domestic deferred tax assets; (2) recent cumulative losses and the Company’s projection of continued losses into 2014; (3) while the Company had the ability to carry back federal net operating losses or credits to utilize against federal taxable income, it estimated it would generate only $1,600,000 in cash refunds (which were received in the fourth quarter of 2014); and (4) the lack of prudent and feasible tax planning strategies. These assessment factors remain essentially unchanged, as the Company remains in a significant cumulative loss position as of March 31, 2015. As a result, management believes a full valuation allowance against all domestic net deferred tax assets is warranted as of March 31, 2015. The valuation allowance against these deferred tax assets may require adjustment in the future based on changes in the mix of temporary differences, changes in tax laws, and operating performance. If and when the Company determines the valuation allowance should be released (i.e., reduced), the adjustment would result in a tax benefit reported in that period’s consolidated statements of operations, the effect of which would be an increase in reported net income. A portion of such an adjustment may be accounted for through an increase to “Additional paid-in capital”, a component of stockholders’ equity. The amount of any such tax benefit associated with release of our valuation allowance in a particular quarter may be material.
	The Company’s subsidiary in Italy, Vicor Italy S.r.l. (“Vicor Italy”), underwent a tax inspection in 2014 for tax years 2009 through 2013, covering corporation, regional and value added taxes. Vicor Italy received a preliminary tax audit report dated June 30, 2014. The Company filed a response to the preliminary tax audit report in the third quarter of 2014. While management believes it is too early to determine the likelihood or amount of potential liability at this time, it does not believe the ultimate impact of this matter will be material to the Company’s financial statements.
	Other than the Vicor Italy matter discussed above there are no other income tax examinations or audits currently in process.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11	Commitments and Contingencies
	At March 31, 2015, the Company had approximately $960,000 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 U.S. District Court for the Eastern District of Texas (the “Texas Action”). This immediately followed a complaint filed by the Company on January 26, 2011, in U.S. District Court for the District of Massachusetts, in which the Company sought a declaratory judgment that its bus converter products do not infringe any valid claim of certain of SynQor’s U.S. patents, and that the claims of those patents are invalid. With respect to the Company, SynQor’s complaint alleges the Company’s products, including, but not limited to, unregulated bus converters used in intermediate bus architecture power supply systems, infringe certain SynQor patents. SynQor seeks, among other items, an injunction against further infringement and an award of unspecified compensatory and enhanced damages, interest, costs and attorney fees. On February 8, 2011, SynQor filed a motion for preliminary injunction seeking an order enjoining the Company from manufacturing, using, selling, and offering for sale in the United States and/or importing into the United States certain identified unregulated bus converters, as well as any other bus converters not significantly different from those products. On February 17, 2011, the Company withdrew its Massachusetts action without prejudice to allow the litigation to proceed in Texas. On May 16, 2011, SynQor announced it was withdrawing its motion for preliminary injunction against the Company. On that date, SynQor also announced it and Ericsson had entered into a definitive settlement agreement, the terms of which were not disclosed. On September 16, 2011, the U.S. District Court for the Eastern District of Texas issued an order setting a trial date of July 7, 2014. On September 20, 2011, SynQor filed an amended complaint in the Texas Action. The amended complaint repeated the allegations of patent infringement against the Company contained in SynQor’s original complaint, and included additional patent infringement allegations with respect to U.S. Patent No. 8,023,290 (“’290 patent”), which was issued on that day. As with SynQor’s original complaint, the amended complaint alleged the Company’s products, including but not limited to the Company’s unregulated bus converters used in intermediate bus architecture power supply systems, infringed the asserted patents. On October 4, 2011, the Company filed an answer and counterclaims to SynQor’s amended complaint, in which the Company alleges the ‘290 patent is unenforceable because it was procured through inequitable conduct before the U.S. Patent and Trademark Office and seeks damages against SynQor for SynQor’s unfair and deceptive trade practices and tortious interference with prospective economic advantage in connection with SynQor’s allegations of patent infringement against the Company. On January 2, 2014, the court issued its claim construction order following a claim construction hearing held on December 17, 2013. On January 16, 2014, the Company filed a motion seeking reconsideration of certain aspects of the court’s claim construction ruling. On March 31, 2014, the court issued an order severing the case against the Company and Cisco into two separate matters, with separate trials to be held with respect to SynQor’s claims against Cisco and SynQor’s claims against the Company. On June 30, 2014, the Company filed a number of motions seeking summary judgment in this matter, including for a finding of no direct, indirect, or willful infringement and for a finding of indefiniteness with respect to U.S. Patent No. 7,272,021. The court has yet to rule on these motions. On October 23, 2014, the court issued an order continuing trial in this matter indefinitely. On January 7, 2015, the Company’s case and that of Cisco were assigned to a new judge within the U.S. District Court for the Eastern District of Texas (the “Texas Court”). On February 6, 2015, SynQor filed a motion to consolidate the Company’s and Cisco’s cases for trial, which was subsequently denied. On March 13, 2015, the U.S. Court of Appeals for the Federal Circuit in Washington, D.C. Circuit issued a ruling invalidating certain claims of a power converter patent (the “’190 patent”) asserted by SynQor against the Company, which is one of four related patents at question in the Texas Action. Challenges to the validity of the remaining claims relating to the ‘190 patent, and to the remaining patents asserted by SynQor against the Company, remain pending before the U.S. Patent and Trademark Office and in the Texas Action. On March 26, 2015, the Texas Court scheduled pre-trial conferences for September 15, 2015, for Cisco’s case and January 13, 2016, for the Company’s case. As of April 30, 2015, the Company has received no notice from the Texas Court regarding the timing of rulings on our summary judgment motions.
	The Company continues to believe that 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 to have a material adverse impact on the Company’s financial position or results of operations.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segment Information	12	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 power converters and configurable products, and also includes the operations of the Company’s Westcor division through its closure in December 2014, the six entities comprising Vicor Custom Power, and the BBU operations of Vicor Japan Company, Ltd. (“VJCL”). The VI Chip segment includes VI Chip Corporation, which designs, develops, manufactures and markets the Company’s factorized power architecture (“FPA”) products. The VI Chip segment also includes the VI Chip business conducted through VJCL. The Picor segment includes Picor Corporation, which designs, develops, manufactures and markets integrated circuits and related products for use in a variety of power management and power system applications. The Picor segment develops these products to be sold as part of the Company’s products or to third parties for separate applications.
	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 significant segment financial data for the three months ended March 31, (in thousands):
			BBU		VI Chip			Picor			Corporate			Eliminations (1)			Total
	2015:00:00
	Net revenues		$	44,878	$	14,180		$	7,109		$	—		$	(2,150	)	$	64,017
	Income (loss) from operations			5,379		(3,488	)		2,017			(298	)		—			3,610
	Total assets			155,737		17,125			7,489			79,483			(98,561	)		161,273
	Depreciation and amortization			1,153		799			97			354			—			2,403
	2014:00:00
	Net revenues		$	43,689	$	9,341		$	2,950		$	—		$	(2,747	)	$	53,233
	Income (loss) from operations			2,312		(6,847	)		(742	)		(162	)		—			(5,439	)
	Total assets			138,770		20,011			4,514			75,130			(75,337	)		163,088
	Depreciation and amortization			1,193		791			101			358			—			2,443
	-1	The elimination for net revenues is principally related to inter-segment revenues of Picor to BBU and VI Chip and for inter-segment revenues of 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_Acco

Impact of Recently Issued Accounting Standards	3 Months Ended
	Mar. 31, 2015
Accounting Changes and Error Corrections [Abstract]
Impact of Recently Issued Accounting Standards	13	Impact of Recently Issued Accounting Standards
	In May 2014, the Financial Accounting Standards Board (“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 will replace most existing revenue recognition guidance in U.S. Generally Accepted Accounting Principles when it becomes effective which, for the Company, will be on January 1, 2017. Early application is not permitted. On April 29, 2015, though, the FASB issued for public comment a proposed Accounting Standards Update (“ASU”) that would defer the effective date of this standard by one year. This ASU is subject to a thirty day public comment period. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect the new guidance will have on its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect the standard will have on its ongoing financial reporting.

ShortTerm_and_LongTerm_Investm1

Short-Term and Long-Term Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Securities	The following is a summary of available-for-sale securities (in thousands):
	31-Mar-15	Cost			Gross		Gross		Estimated
					Unrealized		Unrealized		Fair
					Gains		Losses		Value
	Failed Auction Security	$	3,000		$	—	$	440	$	2,560
	Brokered certificates of deposit		430			2				432
		$	3,430		$	2	$	440	$	2,992
	December 31, 2014	Cost			Gross		Gross		Estimated
					Unrealized		Unrealized		Fair
					Gains		Losses		Value
	Failed Auction Security	$	3,000		$	—	$	425	$	2,575
	Brokered certificates of deposit		700			—		3		697
		$	3,700		$	—	$	428	$	3,272
Amortized Cost and Estimated Fair Value of Available-for-Sale Securities by Contractual Maturities	The amortized cost and estimated fair value of available-for-sale securities on March 31, 2015, by contractual maturities, are shown below (in thousands):
		Cost			Estimated
					Fair Value
	Due in one year or less	$	90		$	90
	Due in two to ten years		340			342
	Due in ten to twenty years		—			—
	Due in twenty to forty years		3,000			2,560
		$	3,430		$	2,992
Rollforward of Credit (Gain) Loss Recognized in Earnings on Available-for-Sale Auction Rate Securities	The following table represents a rollforward of the activity related to the credit loss recognized in earnings on available-for-sale auction rate securities held by the Company for the three months ended March 31 (in thousands):
		2015			2014
	Balance at the beginning of the period	$	84		$	395
	Changes in the amount related to credit loss for which other-than- temporary impairment was not previously recognized		(4	)		—
	Balance at the end of the period	$	80		$	395

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Assets Measured at Fair Value on Recurring Basis	Assets measured at fair value on a recurring basis include the following as of March 31, 2015 (in thousands):
		Using
		Quoted Prices			Significant			Significant			Total Fair
		in Active			Other			Unobservable			Value as of
		Markets			Observable			Inputs			March 31, 2015
		(Level 1)			Inputs			(Level 3)
					(Level 2)
	Cash equivalents:
	Money market funds	$	11,450		$	—		$	—		$	11,450
	Short-term investments:
	Brokered certificates of deposit		—			90			—			90
	Long-term investments:
	Failed Auction Security		—			—			2,560			2,560
	Brokered certificates of deposit		—			342			—			342
	Assets measured at fair value on a recurring basis include the following as of December 31, 2014 (in thousands):
		Using
		Quoted Prices			Significant			Significant			Total Fair
		in Active			Other			Unobservable			Value as of
		Markets			Observable			Inputs			December 31, 2014
		(Level 1)			Inputs			(Level 3)
					(Level 2)
	Cash equivalents:
	Money market funds	$	11,207		$	—		$	—		$	11,207
	Short-term investments:
	Brokered certificates of deposit		—			270			—			270
	Long-term investments:
	Failed Auction Security		—			—			2,575			2,575
	Brokered certificates of deposit		—			427			—			427
Quantitative Information about Level 3 Fair Value Measurements	Quantitative information about Level 3 fair value measurements as of March 31, 2015 are as follows (dollars in thousands):
		Fair Value			Valuation		Unobservable	Weighted
					Technique			Average
							Input
	Failed Auction Security	$	2,560		Discounted		Cumulative probability of earning		0.02	%
					cash flow
							the maximum rate until maturity
							Cumulative probability of principal		94.07	%
							return prior to maturity
							Cumulative probability of default		5.91	%
							Liquidity risk premium		5	%
							Recovery rate in default		40	%
Change in Estimated Fair Values Calculated for Assets Valued on Recurring Basis Utilizing Level 3 Inputs	The change in the estimated fair values calculated for those assets valued on a recurring basis utilizing Level 3 inputs (i.e., the Failed Auction Security) for the three months ended March 31, 2015 was as follows (in thousands):
	Balance at the beginning of the period	$	2,575
	Credit gain on available-for-sale securities included in Other income (expense), net		4
	Loss included in Other comprehensive income (loss)		(19	)
	Balance at the end of the period	$	2,560

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Expense	Stock-based compensation expense for the three months ended March 31 was as follows (in thousands):
		Three Months Ended
		March 31,
		2015		2014
	Cost of revenues	$	61	$	36
	Selling, general and administrative		408		191
	Research and development		94		7
	Total stock-based compensation	$	563	$	234

Net_Income_Loss_per_Share_Tabl

Net Income (Loss) per Share (Tables)	3 Months Ended
	Mar. 31, 2015
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 months ended March 31 (in thousands, except per share amounts):
			Three Months Ended
			March 31,
			2015		2014
	Numerator:
	Net income (loss) attributable to Vicor Corporation		$	3,371	$	(5,378	)
	Denominator:
	Denominator for basic net income (loss) per share-weighted average shares (1)			38,689		38,541
	Effect of dilutive securities:
	Employee stock options (2)			460		—
	Denominator for diluted net income (loss) per share – adjusted weighted-average shares and assumed conversions			39,149		38,541
	Basic net income (loss) per share		$	0.09	$	(0.14	)
	Diluted net income (loss) per share		$	0.09	$	(0.14	)
	-1	Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding.
	-2	Options to purchase 112,929 and 1,981,028 shares of Common Stock for the three months ended March 31, 2015 and 2014, respectively, were not included in the calculation of net loss per share as the effect would have been antidilutive.

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories were as follows (in thousands):
		March 31, 2015		December 31, 2014
	Raw materials	$	17,322	$	18,252
	Work-in-process		3,405		3,339
	Finished goods		4,110		4,737
	Net balance	$	24,837	$	26,328

Severance_and_Other_Charges_Ta

Severance and Other Charges (Tables)	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Summary of Activity Related to Accrued Severance Charges	A summary of the activity related to the accrued severance charges, is as follows (in thousands):
	Balance as of December 31, 2014	$	1,904
	Payments		(591	)
	Balance as of March 31, 2015	$	1,313

Product_Warranties_Tables

Product Warranties (Tables)	3 Months Ended
	Mar. 31, 2015
Guarantees [Abstract]
Product Warranty Activity	Product warranty activity for the three months ended March 31, was as follows (in thousands):
		2015			2014
	Balance at the beginning of the period	$	204		$	283
	Accruals for warranties for products sold in the period		15			24
	Fulfillment of warranty obligations		(32	)		(55	)
	Revisions of estimated obligations		—			(3	)
	Balance at the end of the period	$	187		$	249

Income_Taxes_Tables

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Provision for Income Taxes and Effective Income Tax Rate	The provision for income taxes and the effective income tax rate for the three months ended March 31, were as follows (in thousands):
		2015			2014
	Provision for income taxes	$	139		$	17
	Effective income tax rate		3.9	%		0.3	%

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Significant Segment Financial Data	The following table provides significant segment financial data for the three months ended March 31, (in thousands):
			BBU		VI Chip			Picor			Corporate			Eliminations (1)			Total
	2015:00:00
	Net revenues		$	44,878	$	14,180		$	7,109		$	—		$	(2,150	)	$	64,017
	Income (loss) from operations			5,379		(3,488	)		2,017			(298	)		—			3,610
	Total assets			155,737		17,125			7,489			79,483			(98,561	)		161,273
	Depreciation and amortization			1,153		799			97			354			—			2,403
	2014:00:00
	Net revenues		$	43,689	$	9,341		$	2,950		$	—		$	(2,747	)	$	53,233
	Income (loss) from operations			2,312		(6,847	)		(742	)		(162	)		—			(5,439	)
	Total assets			138,770		20,011			4,514			75,130			(75,337	)		163,088
	Depreciation and amortization			1,193		791			101			358			—			2,443
	-1	The elimination for net revenues is principally related to inter-segment revenues of Picor to BBU and VI Chip and for inter-segment revenues of 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.

ShortTerm_and_LongTerm_Investm2

Short-Term and Long-Term Investments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Unrealized Losses On Short Term And Long Term Investments [Line Items]
Amortized cost of securities	$3,430,000	$3,700,000
Minimum period for which failed auction securities been in unrealized loss position	12 months
Estimated fair value of securities	2,992,000	3,272,000
Gross unrealized losses	440,000	428,000
Aggregate credit loss	80,000	84,000	395,000	395,000
Redemption, net		3,000,000
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 of securities	2,560,000	2,575,000
Gross unrealized losses	440,000	425,000
Aggregate credit loss	80,000
Aggregate temporary impairment loss	$360,000

ShortTerm_and_LongTerm_Investm3

Short-Term and Long-Term Investments - Summary of Available-for-Sale Securities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost	$3,430,000	$3,700,000
Gross Unrealized Gains	2,000
Gross unrealized losses	440,000	428,000
Estimated Fair Value	2,992,000	3,272,000
Failed Auction Security [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	3,000,000	3,000,000
Gross unrealized losses	440,000	425,000
Estimated Fair Value	2,560,000	2,575,000
Brokered Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	430,000	700,000
Gross Unrealized Gains	2,000
Gross unrealized losses		3,000
Estimated Fair Value	$432,000	$697,000

ShortTerm_and_LongTerm_Investm4

Short-Term and Long-Term Investments - Amortized Cost and Estimated Fair Value of Available-for-Sale Securities by Contractual Maturities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Available-for-sale Securities, Debt Maturities [Abstract]
Due in one year or less, Cost	$90
Due in two to ten years, Cost	340
Due in ten to twenty years, Cost	0
Due in twenty to forty years, Cost	3,000
Cost	3,430	3,700
Due in one year or less, Estimated Fair Value	90
Due in two to ten years, Estimated Fair Value	342
Due in ten to twenty years, Estimated Fair Value	0
Due in twenty to forty years, Estimated Fair Value	2,560
Estimated Fair Value	$2,992	$3,272

ShortTerm_and_LongTerm_Investm5

Short-Term and Long-Term Investments - Rollforward of Credit (Gain) Loss Recognized in Earnings on Available-for-Sale Auction Rate Securities (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013
Available-for-sale Securities, Debt Maturities [Abstract]
Balance at the beginning of the period	$84	$395	$395
Changes in the amount related to credit loss for which other-than- temporary impairment was not previously recognized	-4
Balance at the end of the period	$80	$395	$395

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets Measured at Fair Value on Recurring Basis (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	$2,992,000	$3,272,000
Failed Auction Security [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	2,560,000	2,575,000
Recurring [Member] | Short-Term Brokered Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	90,000	270,000
Recurring [Member] | Failed Auction Security [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	2,560,000	2,575,000
Recurring [Member] | Long-Term Brokered Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	342,000	427,000
Recurring [Member] | Money Market Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	11,450,000	11,207,000
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	11,450,000	11,207,000
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-Term Brokered Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	90,000	270,000
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-Term Brokered Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	342,000	427,000
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	$2,560,000	$2,575,000

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Percent of credit loss	2.70%
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 transfers between Level 1 and Level 2	$0

Fair_Value_Measurements_Quanti

Fair Value Measurements - Quantitative Information about Level 3 Fair Value Measurements (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$2,992,000	$3,272,000
Failed Auction Security [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$2,560,000
Valuation Technique	Discounted cash flow
Failed Auction Security [Member] | Significant Unobservable Inputs (Level 3) [Member] | 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	0.02%
Failed Auction Security [Member] | Significant Unobservable Inputs (Level 3) [Member] | 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	94.07%
Failed Auction Security [Member] | Significant Unobservable Inputs (Level 3) [Member] | 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	5.91%
Failed Auction Security [Member] | Significant Unobservable Inputs (Level 3) [Member] | 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%
Failed Auction Security [Member] | Significant Unobservable Inputs (Level 3) [Member] | 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_Change

Fair Value Measurements - Change in Estimated Fair Values Calculated for Assets Valued on Recurring Basis Utilizing Level 3 Inputs (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Balance at the beginning of the period	$2,575
Credit gain on available-for-sale securities included in Other income (expense), net	4
Loss included in Other comprehensive income (loss)	-19
Balance at the end of the period	$2,560

StockBased_Compensation_StockB

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock based compensation	$563	$234
Cost of Revenues [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock based compensation	61	36
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock based compensation	408	191
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock based compensation	$94	$7

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (2007 VI Chip Plan [Member], USD $)	Mar. 31, 2015	Dec. 31, 2010
2007 VI Chip Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-qualified stock options		2,984,250
Unrecognized compensation cost related to performance-based stock options	$570,000

Net_Income_Loss_per_Share_Comp

Net Income (Loss) per Share - Computation of Basic and Diluted Net Income (Loss) per Share (Detail) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Numerator:
Net income (loss) attributable to Vicor Corporation	$3,371	($5,378)
Denominator:
Denominator for basic net income (loss) per share-weighted average shares	38,689	38,541
Effect of dilutive securities:
Employee stock options	460
Denominator for diluted net income (loss) per share - adjusted weighted-average shares and assumed conversions	39,149	38,541
Basic net income (loss) per share	$0.09	($0.14)
Diluted net income (loss) per share	$0.09	($0.14)

Net_Income_Loss_per_Share_Comp1

Net Income (Loss) per Share - Computation of Basic and Diluted Net Income (Loss) per Share (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Options to purchase shares of Common Stock not included in the computation of diluted income per share	112,929	1,981,028

Inventories_Summary_of_Invento

Inventories - Summary of Inventories (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]
Raw materials	$17,322	$18,252
Work-in-process	3,405	3,339
Finished goods	4,110	4,737
Net balance	$24,837	$26,328

Other_Investments_Additional_I

Other Investments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	Agreement
Variable Interest Entity [Line Items]
Ownership interest in investment	27.00%		27.00%
Number of supply agreements with GWS	2
Purchase of components under agreement	$1,057,000	$942,000
GWS [Member]
Variable Interest Entity [Line Items]
Company owed GWS	325,000		170,000
Great Wall Semiconductor Corporation (GWS) [Member]
Variable Interest Entity [Line Items]
Investment in non-voting convertible preferred stock	0		0
Great Wall Semiconductor Corporation (GWS) [Member] | Convertible Preferred Stock [Member]
Variable Interest Entity [Line Items]
Gross investment in non-voting convertible preferred stock	$5,000,000		5,000,000

Severance_and_Other_Charges_Ad

Severance and Other Charges - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Severance charges	$2,207,000
Other restructuring charges		$303,000

Severance_and_Other_Charges_Su

Severance and Other Charges - Summary of Activity Related to Accrued Severance Charges by Segment (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring Reserve, Beginning Balance	$1,904
Payments	-591
Restructuring Reserve, Ending Balance	$1,313

Product_Warranties_Additional_

Product Warranties - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015
Guarantees [Abstract]
Product warranty period	2 years

Product_Warranties_Product_War

Product Warranties - Product Warranty Activity (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Guarantees [Abstract]
Balance at the beginning of the period	$204	$283
Accruals for warranties for products sold in the period	15	24
Fulfillment of warranty obligations	-32	-55
Revisions of estimated obligations		-3
Balance at the end of the period	$187	$249

Income_Taxes_Provision_for_Inc

Income Taxes - Provision for Income Taxes and Effective Income Tax Rate (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Provision for income taxes	$139	$17
Effective income tax rate	3.90%	0.30%

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax benefit recognized	$0	$0
Valuation allowance, deferred tax assets	25,776,000
Deferred tax assets valuation allowance increase			10,241,000
Amount generated in cash refund	$1,600,000

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Capital expenditure commitments	$960,000

Segment_Information_Additional

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015
	Entity
Segment Reporting [Abstract]
Number of entities comprising operating segment	6

Segment_Information_Significan

Segment Information - Significant Segment Financial Data (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues	$64,017	$53,233
Income (loss) from operations	3,610	-5,439
Total assets	161,273	163,088	155,542
Depreciation and amortization	2,403	2,443
Operating Segments [Member] | BBU [Member]
Segment Reporting Information [Line Items]
Net revenues	44,878	43,689
Income (loss) from operations	5,379	2,312
Total assets	155,737	138,770
Depreciation and amortization	1,153	1,193
Operating Segments [Member] | VI Chip [Member]
Segment Reporting Information [Line Items]
Net revenues	14,180	9,341
Income (loss) from operations	-3,488	-6,847
Total assets	17,125	20,011
Depreciation and amortization	799	791
Operating Segments [Member] | Picor [Member]
Segment Reporting Information [Line Items]
Net revenues	7,109	2,950
Income (loss) from operations	2,017	-742
Total assets	7,489	4,514
Depreciation and amortization	97	101
Operating Segments [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	-298	-162
Total assets	79,483	75,130
Depreciation and amortization	354	358
Eliminations [Member]
Segment Reporting Information [Line Items]
Net revenues	-2,150	-2,747
Total assets	($98,561)	($75,337)