Net Income (Loss) per Share - Computation Of Basic And Diluted Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income (loss) attributable to Vicor Corporation	$ 13,012	$ (11)	$ 24,815	$ (1,444)
Denominator:
Denominator for basic net income (loss) per share-weighted average shares	40,120	39,288	39,769	39,177
Effect of dilutive securities:
Employee stock options	1,004		876
Denominator for diluted net income (loss) per share - adjusted weighted-average shares and assumed conversions	41,124	39,288	40,645	39,177
Basic net income (loss) per share	$ 0.32	$ 0.00	$ 0.62	$ (0.04)
Diluted net income (loss) per share	$ 0.32	$ 0.00	$ 0.61	$ (0.04)