Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Research and development tax credit carryforwards	$ 13,967,000	$ 12,503,000
Net operating loss carryforwards	4,902,000	3,393,000
Stock-based compensation	4,066,000	3,993,000
Inventory reserves	3,143,000	2,979,000
Vacation accrual	1,928,000	1,768,000
Investment tax credit carryforwards	1,576,000	1,399,000
Alternative minimum tax credit carryforward	340,000	340,000
Deferred revenue	154,000	192,000
Unrealized loss on investments	136,000	149,000
Warranty reserves	73,000	202,000
Bad debt reserves	52,000	58,000
Other	331,000	735,000
Total deferred tax assets	30,668,000	27,711,000
Less: Valuation allowance for deferred tax assets	(29,274,000)	(25,862,000)
Net deferred tax assets	1,394,000	1,849,000
Deferred tax liabilities:
Prepaid expenses	(654,000)	(713,000)
Depreciation	(406,000)	(787,000)
Patent amortization	(296,000)	(334,000)
Unremitted Vicor Custom Power earnings		(55,000)
Total deferred tax liabilities	(1,356,000)	(1,889,000)
Net deferred tax assets (liabilities)	$ 38,000
Net deferred tax assets (liabilities)		$ (40,000)