Amortization Expense of Acquired Intangibles (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 2,965	$ 3,138
Cost of revenue
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	1,346	1,343
Selling and marketing
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	1,530	1,531
General and administrative
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 89	$ 264