Segment Information - Significant Segment Financial Data (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues	$ 48,085	$ 53,227	$ 52,941	$ 46,027	$ 51,394	$ 48,664	$ 56,119	$ 64,017	$ 200,280	$ 220,194	$ 225,731
Income (loss) from operations									(6,314)	(267)	(14,763)
Total assets	154,067				157,545				154,067	157,545	155,542
Depreciation and amortization									8,438	9,142	9,805
Operating Segments [Member] | BBU [Member]
Segment Reporting Information [Line Items]
Net revenues									151,428	173,064	184,224
Income (loss) from operations									11,750	21,743	15,499
Total assets	196,987				170,939				196,987	170,939	151,923
Depreciation and amortization									4,258	4,538	4,711
Operating Segments [Member] | VI Chip [Member]
Segment Reporting Information [Line Items]
Net revenues									39,947	36,688	34,701
Income (loss) from operations									(16,494)	(21,040)	(29,015)
Total assets	21,389				15,577				21,389	15,577	17,677
Depreciation and amortization									2,235	2,740	3,265
Operating Segments [Member] | Picor [Member]
Segment Reporting Information [Line Items]
Net revenues									16,684	17,304	15,570
Income (loss) from operations									(637)	(290)	(407)
Total assets	8,583				5,369				8,583	5,369	5,691
Depreciation and amortization									545	442	410
Operating Segments [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations									(933)	(680)	(840)
Total assets	73,253				81,824				73,253	81,824	75,758
Depreciation and amortization									1,400	1,422	1,419
Eliminations [Member]
Segment Reporting Information [Line Items]
Net revenues									(7,779)	(6,862)	(8,764)
Total assets	$ (146,145)				$ (116,164)				$ (146,145)	$ (116,164)	$ (95,507)