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Significant Accounting Policies - Computation Of Basic And Diluted Net Income (Loss) Per Share (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Numerator:                      
Net income (loss) attributable to Vicor Corporation $ 1,611 $ (11) $ (459) $ (974) $ (2,688) $ 2,336 $ (544) $ (5,351) $ 167 $ (6,247) $ 4,927
Denominator:                      
Denominator for basic net income (loss) per share-weighted average shares                 39,228 38,842 38,754
Effect of dilutive securities:                      
Employee stock options                 705   392
Denominator for diluted net income (loss) per share - adjusted weighted-average shares and assumed conversions                 39,933 38,842 39,146
Basic net income (loss) per share                 $ 0.00 $ (0.16) $ 0.13
Diluted net income (loss) per share                 $ 0.00 $ (0.16) $ 0.13