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		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net income attributable to Vicor Corporation		$ 2,667	$ 2,563	$ 932	$ 6,849
Denominator:
Denominator for basic net income per share-weighted average shares	[1]	41,643	40,275	41,140	40,252
Effect of dilutive securities:
Employee stock options	[2]	1,742	806	1,840	803
Denominator for diluted net income per share – adjusted weighted-average shares and assumed conversions		43,385	41,081	42,980	41,055
Basic net income per share		$ 0.06	$ 0.06	$ 0.02	$ 0.17
Diluted net income per share		$ 0.06	$ 0.06	$ 0.02	$ 0.17

[1] Denominator represents weighted average number of shares of Common Stock and Class B Common Stock outstanding.

[2] Options to purchase 54,551 and 47,375 shares of Common Stock for the three and six months ended June 30, 2020, respectively, and 44,793 and 79,857 shares of Common Stock for the three and six months ended June 30, 2019, respectively, were not included in the calculations of net income per share as the effect would have been antidilutive.