Amortization Expense of Acquired Intangibles (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 3,174	$ 3,604	$ 6,374	$ 6,569
Cost of revenue
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	1,305	1,638	2,639	2,984
Operating expenses
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 1,869	$ 1,966	$ 3,735	$ 3,585