Vicor (VICR) 10-Q 3 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 19, 2021
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Registrant Name	VICOR CORP
Entity Central Index Key	0000751978
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Trading Symbol	VICR
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Document Transition Report	false
Document Quarterly Report	true
Entity File Number	0-18277
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-2742817
Entity Address, Address Line One	25 Frontage Road
Entity Address, City or Town	Andover
Entity Address, Postal Zip Code	01810
City Area Code	978
Local Phone Number	470-2900
Security Exchange Name	NASDAQ
Entity Address, State or Province	MA
Title of 12(b) Security	Common Stock
Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		31,764,120
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		11,758,218

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 127,411	$ 161,742
Short-term investments	95,719	50,166
Accounts receivable, less allowance of $82 in 2021 and 2020	47,697	40,999
Inventories, net	54,256	57,269
Other current assets	6,954	6,756
Total current assets	332,037	316,932
Long-term deferred tax assets, net	224	226
Long-term investments, net	2,541	2,517
Property, plant and equipment, net	81,124	74,843
Other assets	1,695	1,721
Total assets	417,621	396,239
Current liabilities:
Accounts payable	16,365	14,121
Accrued compensation and benefits	14,485	14,094
Accrued expenses	3,153	2,624
Short-term lease liabilities	1,571	1,629
Sales allowances	1,253	597
Income taxes payable	43	139
Short-term deferred revenue and customer prepayments	6,008	7,309
Total current liabilities	42,878	40,513
Long-term deferred revenue	653	733
Contingent consideration obligations	181	227
Long-term income taxes payable	648	643
Long-term lease liabilities	2,779	2,968
Total liabilities	47,139	45,084
Commitments and contingencies (Note 10)
Vicor Corporation stockholders' equity:
Additional paid-in capital	333,011	328,392
Retained earnings	176,100	161,008
Accumulated other comprehensive loss	(573)	(204)
Treasury stock at cost: 11,634,806 shares in 2021 and 2020	(138,927)	(138,927)
Total Vicor Corporation stockholders' equity	370,164	350,820
Noncontrolling interest	318	335
Total equity	370,482	351,155
Total liabilities and equity	417,621	396,239
Class B Common Stock [Member]
Vicor Corporation stockholders' equity:
Common Stock	118	118
Total equity	118	118
Common Stock [Member]
Vicor Corporation stockholders' equity:
Common Stock	$ 435	$ 433

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) $ in Thousands	Mar. 31, 2021USD ($)Vote$ / sharesshares	Dec. 31, 2020USD ($)Vote$ / sharesshares
Accounts receivable, allowance | $	$ 82	$ 82
Treasury stock, shares	11,634,806	11,634,806
Class B Common Stock [Member]
Common Stock, votes per share | Vote	10	10
Common Stock, par value | $ / shares	$ 0.01	$ 0.01
Common Stock, shares authorized	14,000,000	14,000,000
Common Stock, shares issued	11,758,218	11,758,218
Common Stock, shares outstanding	11,758,218	11,758,218
Common Stock [Member]
Common Stock, votes per share | Vote	1	1
Common Stock, par value | $ / shares	$ 0.01	$ 0.01
Common Stock, shares authorized	62,000,000	62,000,000
Common Stock, shares issued	43,397,118	43,204,671
Common Stock, shares outstanding	31,762,312	31,569,865

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net revenues		$ 88,796	$ 63,401
Cost of revenues		44,096	36,070
Gross margin		44,700	27,331
Operating expenses:
Selling, general and administrative		16,954	16,369
Research and development		13,026	13,335
Total operating expenses		29,980	29,704
Income (loss) from operations		14,720	(2,373)
Other income (expense), net:
Total unrealized gains on available-for-sale securities, net		24	47
Less: portion of gains recognized in other comprehensive income		(23)	(46)
Net credit gains recognized in earnings		1	1
Other income (expense), net		231	147
Total other income (expense), net		232	148
Income (loss) before income taxes		14,952	(2,225)
Benefit for income taxes		(143)	(494)
Consolidated net income (loss)		15,095	(1,731)
Less: Net income attributable to noncontrolling interest		3	4
Net income (loss) attributable to Vicor Corporation		$ 15,092	$ (1,735)
Net income (loss) per common share attributable to Vicor Corporation:
Basic		$ 0.35	$ (0.04)
Diluted		$ 0.34	$ (0.04)
Shares used to compute net income (loss) per common share attributable to Vicor Corporation:
Basic	[1]	43,455	40,635
Diluted		44,841	40,635
[1]	Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Consolidated net income (loss)		$ 15,095	$ (1,731)
Foreign currency translation (losses) gains, net of tax	[1]	(261)	46
Unrealized (losses) gains on available-for-sale securities, net of tax	[1]	(128)	41
Other comprehensive (loss) income		(389)	87
Consolidated comprehensive income (loss)		14,706	(1,644)
Less: Comprehensive (loss) income attributable to noncontrolling interest		(17)	8
Comprehensive income (loss) attributable to Vicor Corporation		$ 14,723	$ (1,652)
[1]	The deferred tax assets associated with foreign currency translation (losses) gains and unrealized (losses) gains on available-for-sale securities are completely offset by a tax valuation allowance as of March 31, 2021 and 2020. Therefore, there is no income tax benefit (provision) recognized for the three months ended March 31, 2021 and 2020.

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Recognized income tax benefit (provision)	$ 0	$ 0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Consolidated net income (loss)	$ 15,095	$ (1,731)
Adjustments to reconcile consolidated net income (loss) to net cash provided by (used for) operating activities:
Depreciation and amortization	2,806	2,711
Stock-based compensation expense, net	1,571	710
Provision for doubtful accounts		43
Increase in long-term income taxes payable	5	4
Decrease in long-term deferred revenue	(80)	(80)
Deferred income taxes	2	(1)
Credit gain on available-for-sale securities	(1)	(1)
(Increase) decrease in other assets	(26)	75
Change in current assets and liabilities, net	(1,599)	(2,639)
Net cash provided by (used for) operating activities	17,773	(909)
Investing activities:
Purchases of short-term investments	(50,706)
Sales or maturities of short-term investments	5,000
Additions to property, plant and equipment	(9,264)	(2,999)
Net cash used for investing activities	(54,970)	(2,999)
Financing activities:
Proceeds from employee stock plans	3,050	2,061
Payment of contingent consideration obligations	(46)	(89)
Net cash provided by financing activities	3,004	1,972
Effect of foreign exchange rates on cash	(138)	19
Net decrease in cash and cash equivalents	(34,331)	(1,917)
Cash and cash equivalents at beginning of period	161,742	84,668
Cash and cash equivalents at end of period	$ 127,411	$ 82,751

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total Vicor Corporation Stockholders' Equity [Member]	Noncontrolling Interest [Member]	Class B Common Stock [Member]
Beginning Balance at Dec. 31, 2019	$ 205,870	$ 405	$ 201,251	$ 143,098	$ (383)	$ (138,927)	$ 205,562	$ 308	$ 118
Issuance of Common Stock under employee stock plans	2,061	2	2,059				2,061
Stock-based compensation expense	710		710				710
Components of comprehensive income, net of tax:
Net income	(1,731)			(1,735)			(1,735)	4
Other comprehensive loss	87				83		83	4
Total comprehensive income (loss)	(1,644)						(1,652)	8
Ending Balance at Mar. 31, 2020	206,997	407	204,020	141,363	(300)	(138,927)	206,681	316	118
Beginning Balance at Dec. 31, 2020	351,155	433	328,392	161,008	(204)	(138,927)	350,820	335	118
Issuance of Common Stock under employee stock plans	3,050	2	3,048				3,050
Stock-based compensation expense	1,571		1,571				1,571
Components of comprehensive income, net of tax:
Net income	15,095			15,092			15,092	3
Other comprehensive loss	(389)				(369)		(369)	(20)
Total comprehensive income (loss)	14,706						14,723	(17)
Ending Balance at Mar. 31, 2021	$ 370,482	$ 435	$ 333,011	$ 176,100	$ (573)	$ (138,927)	$ 370,164	$ 318	$ 118

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2021
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 (the “SEC”). 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, 2021 are not necessarily indicative of the results that may be expected for any other interim period or the year ending December 31, 2021. The balance sheet at December 31, 2020 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 10-K”).

Inventories

Inventories	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Inventories	2. Inventories Inventories are valued at the lower of cost (determined using the first-in, first-out Inventory that is estimated to be excess, obsolete or unmarketable is written down to net realizable value. The Company’s estimation process for assessing net realizable value is based upon management’s estimate of expected future utility which is derived based on backlog, 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, 2021 December 31, 2020 Raw materials $ 39,924 $ 42,556 Work-in-process 9,271 7,424 Finished goods 5,061 7,289 $ 54,256 $ 57,269

Short-Term and Long-Term Invest

Short-Term and Long-Term Investments	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Short-Term and Long-Term Investments	3. Short-Term and Long-Term Investments As of March 31, 2021, the Company held $95,719,000 of short-term investments, consisting of obligations of the U.S. Treasury, all of which were debt securities with original maturities greater than three months but less than one year at the time of purchase. As of March 31, 2021 and December 31, 2020, 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 March 31, 2021, 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, 2021. Details of our investments are as follows (in thousands): March 31, 2021 Cash and Short-Term Long-Term Measured at fair value: Available-for-sale Money Market Funds $ 43,728 $ — $ — U.S. Treasury Obligations — 95,719 — Failed Auction Security — — 2,541 Total 43,728 95,719 2,541 Other measurement basis: Cash on hand 83,683 — — Total $ 127,411 $ 95,719 $ 2,541 December 31, 2020 Cash and Short-Term Long-Term Measured at fair value: Available-for-sale Money Market Funds $ 69,493 $ — $ — U.S. Treasury Obligations 19,998 50,166 — Failed Auction Security — — 2,517 Total 89,491 50,166 2,517 Other measurement basis: Cash on hand 72,251 — — Total $ 161,742 $ 50,166 $ 2,517 The following is a summary of the available-for-sale March 31, 2021 Cost Gross Gross Estimated U.S. Treasury Obligations $ 95,716 $ 3 $ — $ 95,719 Failed Auction Security 3,000 — 459 2,541 December 31, 2020 Cost Gross Gross Estimated U.S. Treasury Obligations $ 70,172 $ — $ 8 $ 70,164 Failed Auction Security 3,000 — 483 2,517 As of March 31, 2021, the Failed Auction Security had been in an unrealized loss position for greater than 12 months. The amortized cost and estimated fair value of the available-for-sale contractual maturities, are shown below (in thousands): Cost Estimated U.S. Treasury Obligations: Maturities greater than three months but less than one year $ 95,716 $ 95,719 $ 95,716 $ 95,719 Cost Estimated Failed Auction Security: Due in twenty to forty years $ 3,000 $ 2,541 Based on the fair value measurements described in Note 4, the fair value of the Failed Auction Security on March 31, 2021, with a par value of $3,000,000, was estimated by the Company to be approximately $2,541,000. The gross unrealized loss of $459,000 on the Failed Auction Security consists of two types of estimated loss: an aggregate credit loss of $32,000 and an aggregate temporary impairment of $427,000. 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. The following table represents a rollforward of the activity related to the credit loss recognized in earnings on the Failed Auction Security for the three months ended March 31 (in thousands): 2021 2020 Balance at the beginning of the period $ 33 $ 37 Reductions in the amount related to credit gain for which other-than- temporary impairment was not previously recognized (1 ) (1 ) Balance at the end of the period $ 32 $ 36 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, its short-term investments 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, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. 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 March 31, 2021 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 43,728 $ — $ — $ 43,728 Short-term investments: U.S. Treasury Obligations 95,719 — — 95,719 Long-term investment: Failed Auction Security — — 2,541 2,541 Liabilities: Contingent consideration obligations — — (181 ) (181 ) Assets and liabilities measured at fair value on a recurring basis included the following as of December 31, 2020 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 69,493 $ — $ — $ 69,493 U.S. Treasury Obligations 19,998 — — 19,998 Short-term investments: U.S. Treasury Obligations 50,166 — — 50,166 Long-term investment: Failed Auction Security — — 2,517 2,517 Liabilities: Contingent consideration obligations — — (227 ) (227 ) As of March 31, 2021, 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, 2021. The major assumptions used in preparing the DCF model were similar to those described in Note 5 - Fair Value Measurements in the Notes to the Consolidated Financial Statements contained in the Company’s 2020 Form 10-K. Quantitative information about Level 3 fair value measurements as of March 31, 2021 is as follows (dollars in thousands): Fair Value Valuation Unobservable Input Weighted Failed Auction Security $ 2,541 Discounted cash flow Cumulative probability of earning the maximum rate until maturity 0.14 % Cumulative probability of principal return prior to maturity 93.95 % Cumulative probability of default 5.91 % 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 three months ended March 31, 2021 was as follows (in thousands): Balance at the beginning of the period $ 2,517 Credit gain on available-for-sale 1 Gain included in Other comprehensive income 23 Balance at the end of the period $ 2,541 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 three months ended March 31, 2021 was as follows (in thousands): Balance at the beginning of the period $ 227 Payments (46 ) Balance at the end of the period $ 181 There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2021.

Revenues

Revenues	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenues	5. Revenues The following tables present the Company’s net revenues disaggregated by geography based on the location of the customer, by product line (in thousands): Three Months Ended March 31, 2021 Brick Products Advanced Products Total United States $ 18,583 $ 8,549 $ 27,132 Europe 8,196 995 9,191 Asia Pacific 27,328 24,653 51,981 All other 352 140 492 $ 54,459 $ 34,337 $ 88,796 Three Months Ended March 31, 2020 Brick Products Advanced Products Total United States $ 25,970 $ 7,597 $ 33,567 Europe 4,568 879 5,447 Asia Pacific 13,656 9,376 23,032 All other 1,323 32 1,355 $ 45,517 $ 17,884 $ 63,401 The following tables present the Company’s net revenues disaggregated by the category of revenue, by product line (in thousands): Three Months Ended March 31, 2021 Brick Products Advanced Products Total Direct customers, contract manufacturers and non-stocking $ 43,808 $ 29,057 $ 72,865 Stocking distributors, net of sales allowances 10,547 4,138 14,685 Non-recurring 104 1,071 1,175 Royalties — 53 53 Other — 18 18 $ 54,459 $ 34,337 $ 88,796 Three Months Ended March 31, 2020 Brick Products Advanced Products Total Direct customers, contract manufacturers and non-stocking $ 35,739 $ 14,767 $ 50,506 Stocking distributors, net of sales allowances 9,622 3,062 12,684 Non-recurring 156 37 193 Other — 18 18 $ 45,517 $ 17,884 $ 63,401 The following table presents the changes in certain contract assets and (liabilities) (in thousands): March 31, 2021 December 31, Change Accounts receivable $ 47,697 $ 40,999 $ 6,698 Short-term deferred revenue and customer prepayments (6,008 ) (7,309 ) 1,301 Long-term deferred revenue (653 ) (733 ) 80 Deferred expenses 1,726 1,650 76 Sales allowances (1,253 ) (597 ) (656 ) The increase in accounts receivable was primarily due to an increase in net revenues of approximately $5,308,000 in March 2021 compared to December 2020. Deferred expenses are included in Other current assets in the accompanying Condensed Consolidated Balance Sheets. The Company records deferred revenue, which represents a contract liability, when cash payments are received or due in advance of performance under a contract with a customer. The Company recognized revenue of approximately $671,000 and $36,000 for the three months ended March 31, 2021 and 2020, respectively, that was included in deferred revenue at the beginning of the

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	6. Stock-Based Compensation The Company uses the Black-Scholes option pricing model to calculate the fair value of stock option awards, whether they possess time-based vesting provisions or performance-based vesting provisions, and awards granted under the Vicor Corporation 2017 Employee Stock Purchase Plan (“ESPP”), as of their grant date. Stock-based compensation expense was as follows (in thousands): Three Months Ended 2021 2020 Cost of revenues $ 228 $ 119 Selling, general and administrative 853 437 Research and development 490 154 Total stock-based compensation $ 1,571 $ 710 Compensation expense by type of award was as follows (in thousands): Three Months Ended 2021 2020 Stock options $ 1,331 $ 506 ESPP 240 204 Total stock-based compensation $ 1,571 $ 710 The increase in stock option compensation expense for the three months ended March 31, 2021 compared to the three months ended March 31, 2020, was primarily due to an increase in the number of stock options granted and higher stock-based compensation expense associated with June 2020 stock option awards.

Rental Income

Rental Income	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Rental Income	7. Rental Income Income, net under the Company’s operating lease agreement, for its owned facility leased to a third party in California, was approximately $198,000 for the three months ended March 31, 2021 and 2020.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes The tax benefit 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 benefit for income taxes and the effective income tax rates were as follows (dollars in thousands): Three Months Ended 2021 2020 Benefit for income taxes $ (143 ) $ (494 ) Effective income tax rate (1.0 )% (22.2 )% The effective tax rates were lower than the statutory tax rates for the three months ended March 31, 2021 and 2020 primarily due to the Company’s full valuation allowance position against domestic deferred tax assets. The benefit for income taxes for the three months ended March 31, 2021 and 2020 included estimated foreign income taxes and estimated state taxes in jurisdictions in which the Company does not have sufficient net operating loss carryforwards. As of March 31, 2021, the Company had a valuation allowance of approximately $37,856,000 against all net domestic 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. While recent positive operating results, as a result of increases in bookings, caused the Company to be in a cumulative income position as of March 31, 2021, the Company faces uncertainties in forecasting its operating results due to the continued impact of the COVID-19 COVID-19

Net Income (Loss) per Share

Net Income (Loss) per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Income (Loss) per Share	9. Net Income (Loss) per Share The following table sets forth the computation of basic and diluted net income (loss) per share (in thousands, except per share amounts): Three Months Ended 2021 2020 Numerator: Net income (loss) attributable to Vicor Corporation $ 15,092 $ (1,735 ) Denominator: Denominator for basic net income per share-weighted average shares (1) 43,455 40,635 Effect of dilutive securities: Employee stock options (2) 1,386 — Denominator for diluted net income per share – adjusted weighted-average shares and assumed conversions 44,841 40,635 Basic net income (loss) per share $ 0.35 $ (0.04 ) Diluted net income (loss) per share $ 0.34 $ (0.04 ) (1) Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding. (2) Options to purchase 40,339 and 2,615,335 shares of Common Stock for the three months ended March 31, 2021 and 2020, respectively, were not included in the calculations of net income per share as the effect would have been antidilutive.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies At March 31, 2021, the Company had approximately $11,457,000 of capital expenditure commitments, principally for manufacturing equipment. In addition to these commitments, the Company had, in the aggregate, approximately $38,000,000 of remaining budgeted capital expenditures in 2021 associated with the construction of a 90,000 sq. ft. addition to the Company’s existing manufacturing facility and the installation of new production equipment. The Company is the defendant in a patent infringement lawsuit originally filed on January 28, 2011 by SynQor, Inc. (“SynQor”) in the U.S. District Court for the Eastern District of Texas (the “Texas Action”). The complaint, as amended, alleges 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, 7,564,702, and 8,023,290 (“the ‘190 patent”, “the ‘021 patent”, “the ‘702 patent”, and “the ‘290 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. The Company has denied that its products infringe any of the SynQor patents, and has asserted that the SynQor patents are invalid and/or unenforceable. The Company has also asserted counterclaims seeking damages from SynQor for deceptive trade practices and tortious interference with prospective economic advantage arising from SynQor’s attempted enforcement of its patents against the Company. On May 23, 2016, after extensive discovery, the Texas Action was stayed by the court pending completion of certain inter partes reexamination (“IPRx”) proceedings at the United States Patent and Trademark Office (“USPTO”) (including any appeals from such proceedings to the Federal Circuit (as defined below)) concerning the SynQor patents, which are described below. That stay remains in force. On March 17, 2021, SynQor filed a motion to lift the stay in the Texas Action. The Company has opposed that motion, which remains pending. In 2011, in response to the filing of the Texas Action, the Company initiated IPRx proceedings at the USPTO challenging the validity of all claims that were asserted against the Company by SynQor. The current status of these proceedings is as follows. Regarding the ‘190 patent IPRx, the United States Court of Appeals for the Federal Circuit (the “Federal Circuit”) issued a decision on March 13, 2015, determining that certain claims were invalid and remanding the matter to the Patent Trial and Appeal Board (“PTAB”) of the USPTO for further proceedings. On February 20, 2019, the PTAB issued a decision finding that all of the remaining challenged claims were unpatentable. SynQor appealed that decision. On February 22, 2021, the Federal Circuit issued a decision in that appeal. In a 2-1 en banc On August 30, 2017, the Federal Circuit issued rulings with regard to the IPRx proceedings 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. On February 20, 2019, the PTAB issued a decision affirming the examiner’s rejections of all challenged claims. SynQor has filed an appeal of that decision in the Federal Circuit. That appeal has been stayed pending resolution of the pending appeal regarding the ‘190 patent IPRx. 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. On February 20, 2019, the PTAB issued a decision reversing its prior affirmance of the examiner’s non-adoption On October 31, 2017, the Company filed a request with the USPTO for ex parte reexamination (“EPRx”) of the asserted claims of the ‘702 patent, based on different prior art references than had been at issue in the previous IPRx of the ‘702 patent. On August 6, 2018, the Company filed a similar request with the USPTO for EPRx of the asserted claims of the ‘190 patent, based on different prior art references than had been at issue in the previous IPRx of the ‘190 patent. On December 18, 2020, the PTAB issued rulings upholding the validity of the asserted claims in the EPRx proceedings for both the ‘702 and ‘190 patents. Accordingly, both of those proceedings are now terminated. On January 23, 2018, the 20-year 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, it 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.

Impact of Recently Issued Accou

Impact of Recently Issued Accounting Standards	3 Months Ended
	Mar. 31, 2021
Accounting Changes and Error Corrections [Abstract]
Impact of Recently Issued Accounting Standards	11. Impact of Recently Issued Accounting Standards In December 2019, the Financial Accounting Standards Board (“FASB”) issued guidance designed to simplify the accounting for income taxes by eliminating certain exceptions to the general principles in Topic 740, Income Taxes, and also improve consistent application of and simplify U.S. GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This new guidance was effective for the Company for its fiscal year beginning after December 15, 2020, with early adoption permitted. The Company adopted the new guidance as of January 1, 2021. The adoption did not have a material impact on the Company’s consolidated financial statements and disclosures. Other new pronouncements issued but not effective until after March 31, 2021 are not expected to have a material impact on the Company’s consolidated financial statements.

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories were as follows (in thousands): March 31, 2021 December 31, 2020 Raw materials $ 39,924 $ 42,556 Work-in-process 9,271 7,424 Finished goods 5,061 7,289 $ 54,256 $ 57,269

Short-Term and Long-Term Inve_2

Short-Term and Long-Term Investments (Tables)	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Summary of Investment	Details of our investments are as follows (in thousands): March 31, 2021 Cash and Short-Term Long-Term Measured at fair value: Available-for-sale Money Market Funds $ 43,728 $ — $ — U.S. Treasury Obligations — 95,719 — Failed Auction Security — — 2,541 Total 43,728 95,719 2,541 Other measurement basis: Cash on hand 83,683 — — Total $ 127,411 $ 95,719 $ 2,541 December 31, 2020 Cash and Short-Term Long-Term Measured at fair value: Available-for-sale Money Market Funds $ 69,493 $ — $ — U.S. Treasury Obligations 19,998 50,166 — Failed Auction Security — — 2,517 Total 89,491 50,166 2,517 Other measurement basis: Cash on hand 72,251 — — Total $ 161,742 $ 50,166 $ 2,517
Summary of Available-for-Sale Securities	The following is a summary of the available-for-sale March 31, 2021 Cost Gross Gross Estimated U.S. Treasury Obligations $ 95,716 $ 3 $ — $ 95,719 Failed Auction Security 3,000 — 459 2,541 December 31, 2020 Cost Gross Gross Estimated U.S. Treasury Obligations $ 70,172 $ — $ 8 $ 70,164 Failed Auction Security 3,000 — 483 2,517
Cost and Estimated Fair Value of Failed Auction Security by Contractual Maturities	The amortized cost and estimated fair value of the available-for-sale contractual maturities, are shown below (in thousands): Cost Estimated U.S. Treasury Obligations: Maturities greater than three months but less than one year $ 95,716 $ 95,719 $ 95,716 $ 95,719 Cost Estimated Failed Auction Security: Due in twenty to forty years $ 3,000 $ 2,541
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 three months ended March 31 (in thousands): 2021 2020 Balance at the beginning of the period $ 33 $ 37 Reductions in the amount related to credit gain for which other-than- temporary impairment was not previously recognized (1 ) (1 ) Balance at the end of the period $ 32 $ 36

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
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 March 31, 2021 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 43,728 $ — $ — $ 43,728 Short-term investments: U.S. Treasury Obligations 95,719 — — 95,719 Long-term investment: Failed Auction Security — — 2,541 2,541 Liabilities: Contingent consideration obligations — — (181 ) (181 ) Assets and liabilities measured at fair value on a recurring basis included the following as of December 31, 2020 (in thousands): Using Quoted Prices Significant Significant Total Fair Cash equivalents: Money market funds $ 69,493 $ — $ — $ 69,493 U.S. Treasury Obligations 19,998 — — 19,998 Short-term investments: U.S. Treasury Obligations 50,166 — — 50,166 Long-term investment: Failed Auction Security — — 2,517 2,517 Liabilities: Contingent consideration obligations — — (227 ) (227 )
Quantitative Information about Level 3 Fair Value Measurements	Quantitative information about Level 3 fair value measurements as of March 31, 2021 is as follows (dollars in thousands): Fair Value Valuation Unobservable Input Weighted Failed Auction Security $ 2,541 Discounted cash flow Cumulative probability of earning the maximum rate until maturity 0.14 % Cumulative probability of principal return prior to maturity 93.95 % Cumulative probability of default 5.91 % 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 three months ended March 31, 2021 was as follows (in thousands): Balance at the beginning of the period $ 2,517 Credit gain on available-for-sale 1 Gain included in Other comprehensive income 23 Balance at the end of the period $ 2,541
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 three months ended March 31, 2021 was as follows (in thousands): Balance at the beginning of the period $ 227 Payments (46 ) Balance at the end of the period $ 181

Revenues (Tables)

Revenues (Tables)	3 Months Ended
	Mar. 31, 2021
Summary of Net Revenues Based On Geography Location	The following tables present the Company’s net revenues disaggregated by geography based on the location of the customer, by product line (in thousands): Three Months Ended March 31, 2021 Brick Products Advanced Products Total United States $ 18,583 $ 8,549 $ 27,132 Europe 8,196 995 9,191 Asia Pacific 27,328 24,653 51,981 All other 352 140 492 $ 54,459 $ 34,337 $ 88,796 Three Months Ended March 31, 2020 Brick Products Advanced Products Total United States $ 25,970 $ 7,597 $ 33,567 Europe 4,568 879 5,447 Asia Pacific 13,656 9,376 23,032 All other 1,323 32 1,355 $ 45,517 $ 17,884 $ 63,401
Summary of Net Revenues Disaggregated by Geography	The following tables present the Company’s net revenues disaggregated by the category of revenue, by product line (in thousands): Three Months Ended March 31, 2021 Brick Products Advanced Products Total Direct customers, contract manufacturers and non-stocking $ 43,808 $ 29,057 $ 72,865 Stocking distributors, net of sales allowances 10,547 4,138 14,685 Non-recurring 104 1,071 1,175 Royalties — 53 53 Other — 18 18 $ 54,459 $ 34,337 $ 88,796 Three Months Ended March 31, 2020 Brick Products Advanced Products Total Direct customers, contract manufacturers and non-stocking $ 35,739 $ 14,767 $ 50,506 Stocking distributors, net of sales allowances 9,622 3,062 12,684 Non-recurring 156 37 193 Other — 18 18 $ 45,517 $ 17,884 $ 63,401
Summary of Changes in Contract Assets And Liabilities	The following table presents the changes in certain contract assets and (liabilities) (in thousands): March 31, 2021 December 31, Change Accounts receivable $ 47,697 $ 40,999 $ 6,698 Short-term deferred revenue and customer prepayments (6,008 ) (7,309 ) 1,301 Long-term deferred revenue (653 ) (733 ) 80 Deferred expenses 1,726 1,650 76 Sales allowances (1,253 ) (597 ) (656 )

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Stock-Based Compensation Expense	Stock-based compensation expense was as follows (in thousands): Three Months Ended 2021 2020 Cost of revenues $ 228 $ 119 Selling, general and administrative 853 437 Research and development 490 154 Total stock-based compensation $ 1,571 $ 710
Summary of Compensation Expense by Type of Award	Compensation expense by type of award was as follows (in thousands): Three Months Ended 2021 2020 Stock options $ 1,331 $ 506 ESPP 240 204 Total stock-based compensation $ 1,571 $ 710

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Provision For Income Taxes And Effective Income Tax Rate Table Text Block [Table Text Block]	The benefit for income taxes and the effective income tax rates were as follows (dollars in thousands): Three Months Ended 2021 2020 Benefit for income taxes $ (143 ) $ (494 ) Effective income tax rate (1.0 )% (22.2 )%

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Income Per Share	The following table sets forth the computation of basic and diluted net income (loss) per share (in thousands, except per share amounts): Three Months Ended 2021 2020 Numerator: Net income (loss) attributable to Vicor Corporation $ 15,092 $ (1,735 ) Denominator: Denominator for basic net income per share-weighted average shares (1) 43,455 40,635 Effect of dilutive securities: Employee stock options (2) 1,386 — Denominator for diluted net income per share – adjusted weighted-average shares and assumed conversions 44,841 40,635 Basic net income (loss) per share $ 0.35 $ (0.04 ) Diluted net income (loss) per share $ 0.34 $ (0.04 ) (1) Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding. (2) Options to purchase 40,339 and 2,615,335 shares of Common Stock for the three months ended March 31, 2021 and 2020, respectively, were not included in the calculations of net income per share as the effect would have been antidilutive.

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Raw materials	$ 39,924	$ 42,556
Work-in-process	9,271	7,424
Finished goods	5,061	7,289
Net balance	$ 54,256	$ 57,269

Short-Term and Long-Term Inve_3

Short-Term and Long-Term Investments - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Unrealized Losses On Short Term And Long Term Investments [Line Items]
Short Term Investments	$ 95,719,000	$ 50,166,000
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	$ 2,541,000	2,517,000
Gross Unrealized Losses	459,000	483,000
Aggregate credit loss	32,000	$ 33,000	$ 36,000	$ 37,000
Aggregate temporary impairment loss	$ 427,000

Short-Term and Long-Term Inve_4

Short-Term and Long-Term Investments - Summary of Investment (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	$ 127,411	$ 161,742
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	95,719	50,166
Other Long-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	2,541	2,517
Estimate of Fair Value Measurement [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	43,728	89,491
Estimate of Fair Value Measurement [Member] | Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	95,719	50,166
Estimate of Fair Value Measurement [Member] | Other Long-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	2,541	2,517
Estimate of Fair Value Measurement [Member] | Auction Rate Securities [Member] | Other Long-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	2,541	2,517
Estimate of Fair Value Measurement [Member] | Money Market Funds [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	43,728	69,493
Estimate of Fair Value Measurement [Member] | US Treasury Obligations [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale		19,998
Estimate of Fair Value Measurement [Member] | US Treasury Obligations [Member] | Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	95,719	50,166
Portion at Other than Fair Value Measurement [Member] | Cash [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale	$ 83,683	$ 72,251

Short-Term and Long-Term Inve_5

Short-Term and Long-Term Investments - Summary of Available-for-Sale Securities (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
US Treasury Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	$ 95,716,000	$ 70,172,000
Gross Unrealized Gains	3,000
Gross Unrealized Losses		8,000
Estimated Fair Value	95,719,000	70,164,000
Failed Auction Security [Member]
Debt Securities, Available-for-sale [Line Items]
Cost	3,000,000	3,000,000
Gross Unrealized Losses	459,000	483,000
Estimated Fair Value	$ 2,541,000	$ 2,517,000

Short-Term and Long-Term Inve_6

Short-Term and Long-Term Investments - Amortized Cost and Estimated Fair Value of Available-for-Sale Securities by Contractual Maturities (Detail) $ in Thousands	Mar. 31, 2021USD ($)
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 95,716
Available For Sale Debt Securities Estimated Fair Value	95,719
Failed Auction Security [Member]
Schedule of Available-for-sale Securities [Line Items]
Due in twenty to forty years, Cost	3,000
Due in twenty to forty years, Estimated Fair Value	2,541
US Treasury Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturities greater than three months but less than one year, Cost	95,716
Maturities greater than three months but less than one year, Estimated Fair Value	$ 95,719

Short-Term and Long-Term Inve_7

Short-Term and Long-Term Investments - Rollforward of Credit (Gain) Loss Recognized in Earnings on Available-for-Sale Auction Rate Securities (Detail) - Failed Auction Security [Member] - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Balance at the beginning of the period	$ 33,000	$ 37,000
Reductions in the amount related to credit gain for which other-than- temporary impairment was not previously recognized	(1,000)	(1,000)
Balance at the end of the period	$ 32,000	$ 36,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Contingent Consideration Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liabilities, fair value on recurring basis	$ (181,000)	$ (227,000)
Failed Auction Security [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	2,541,000	2,517,000
Failed Auction Security [Member] | Other Long-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	2,541,000	2,517,000
US Treasury Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	95,719,000	19,998,000
Estimated Fair Value	95,719,000	70,164,000
US Treasury Obligations [Member] | Short-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value		50,166,000
Money Market Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	43,728,000	69,493,000
Recurring [Member] | Quoted Prices in Active Markets (Level 1) [Member] | US Treasury Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	95,719,000	19,998,000
Recurring [Member] | Quoted Prices in Active Markets (Level 1) [Member] | US Treasury Obligations [Member] | Short-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value		50,166,000
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	43,728,000	69,493,000
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	(181,000)	(227,000)
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Failed Auction Security [Member] | Other Long-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Estimated Fair Value	$ 2,541,000	$ 2,517,000

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	3 Months Ended
	Mar. 31, 2021USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$ 2,541
Cumulative Probability of Earning Maximum Rate Until Maturity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation Technique	Discounted cash flow
Unobservable Input	Cumulative probability of earning the maximum rate until maturity
Weighted Average Interest Rate	0.14%
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	93.95%
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%
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	3 Months Ended
	Mar. 31, 2021USD ($)
Fair Value Disclosures [Abstract]
Balance at the beginning of the period	$ 2,517
Credit gain on available-for-sale security included in Other income (expense), net	1
Gain included in Other comprehensive income	23
Balance at the end of the period	$ 2,541

Fair Value Measurements - Cha_2

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	3 Months Ended
	Mar. 31, 2021USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at the beginning of the period	$ 227
Payments	(46)
Balance at the end of the period	$ 181

Revenues - Summary of Net Reven

Revenues - Summary of Net Revenues Disaggregated by Geography (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 88,796	$ 63,401
Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	54,459	45,517
Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	34,337	17,884
United States [Member]
Disaggregation of Revenue [Line Items]
Revenue	27,132	33,567
United States [Member] | Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	18,583	25,970
United States [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	8,549	7,597
Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue	9,191	5,447
Europe [Member] | Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	8,196	4,568
Europe [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	995	879
Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Revenue	51,981	23,032
Asia Pacific [Member] | Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	27,328	13,656
Asia Pacific [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	24,653	9,376
All Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	492	1,355
All Other [Member] | Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	352	1,323
All Other [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 140	$ 32

Revenues - Summary of Net Rev_2

Revenues - Summary of Net Revenues Disaggregated by Category (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 88,796	$ 63,401
Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	54,459	45,517
Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	34,337	17,884
Direct Customers, Contract Manufacturers and Non-stocking Distributors [Member]
Disaggregation of Revenue [Line Items]
Revenue	72,865	50,506
Direct Customers, Contract Manufacturers and Non-stocking Distributors [Member] | Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	43,808	35,739
Direct Customers, Contract Manufacturers and Non-stocking Distributors [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	29,057	14,767
Stocking Distributors, Net of Sales Allowances [Member]
Disaggregation of Revenue [Line Items]
Revenue	14,685	12,684
Stocking Distributors, Net of Sales Allowances [Member] | Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	10,547	9,622
Stocking Distributors, Net of Sales Allowances [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	4,138	3,062
Non-recurring Engineering [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,175	193
Non-recurring Engineering [Member] | Brick Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	104	156
Non-recurring Engineering [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,071	37
Royalties [Member]
Disaggregation of Revenue [Line Items]
Revenue	53
Royalties [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	53
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	18	18
Other [Member] | Advanced Products [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 18	$ 18

Revenues - Summary of Changes i

Revenues - Summary of Changes in Certain Contract Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Accounts receivable	$ 47,697	$ 40,999
Short-term deferred revenue and customer prepayments	(6,008)	(7,309)
Long-term deferred revenue	(653)	(733)
Deferred expenses	1,726	1,650
Sales allowances	(1,253)	$ (597)
Accounting Standards Update 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Accounts receivable	6,698
Short-term deferred revenue and customer prepayments	1,301
Long-term deferred revenue	80
Deferred expenses	76
Sales allowances	$ (656)

Revenues - Additional Informati

Revenues - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Increase in net revenues	$ 5,308,000
Deferred Revenue, Revenue Recognized	$ 671,000	$ 36,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 1,571	$ 710
Cost of Revenues [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	228	119
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	853	437
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 490	$ 154

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Compensation Expense by Type of Award (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 1,571	$ 710
Stock Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	1,331	506
ESPP [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 240	$ 204

Rental Income - Additional info

Rental Income - Additional information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Lease income	$ 198,000	$ 198,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail)	Mar. 31, 2021USD ($)
Income Tax Disclosure [Line Items]
Valuation allowance, deferred tax assets	$ 37,856,000

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes and Effective Income Tax Rates (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Benefit for income taxes	$ (143)	$ (494)
Effective income tax rate	(1.00%)	(22.20%)

Net Income per Share - Computat

Net Income per Share - Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income (loss) attributable to Vicor Corporation		$ 15,092	$ (1,735)
Denominator:
Denominator for basic net income per share-weighted average shares	[1]	43,455	40,635
Effect of dilutive securities:
Employee stock options	[2]	1,386
Denominator for diluted net income per share – adjusted weighted-average shares and assumed conversions		44,841	40,635
Basic net income (loss) per share		$ 0.35	$ (0.04)
Diluted net income (loss) per share		$ 0.34	$ (0.04)
[1]	Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding.
[2]	Options to purchase 40,339 and 2,615,335 shares of Common Stock for the three months ended March 31, 2021 and 2020, respectively, were not included in the calculations of net income per share as the effect would have been antidilutive.

Net Income per Share - Comput_2

Net Income per Share - Computation of Basic and Diluted Net Income Per Share (Parenthetical) (Detail) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Options to purchase shares of Common Stock not included in the computation of diluted income per share	40,339	2,615,335

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Mar. 31, 2021USD ($)ft²
Commitments and Contingencies Disclosure [Abstract]
Capital expenditure commitments	$ 11,457,000
Budgeted capital expenditures	$ 38,000,000
Area of Land | ft²	90,000