Commitments and Contingencies - Summary of Warranty Accrual Included in Accrued Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 3,913	$ 4,242	$ 3,606
Accrual for current period warranties	5,655	5,470	7,278
Balance assumed from TVN acquisition	1,012
Changes in liability related to pre-existing warranties	(173)	(92)	3
Warranty costs incurred	(5,545)	(5,707)	(6,645)
Balance at end of period	$ 4,862	$ 3,913	$ 4,242