Amortization Expense of Acquired Intangibles (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 3,119	$ 3,424	$ 6,257	$ 7,180
Cost of revenue
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	1,347	1,444	2,690	3,284
Selling and marketing
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	1,534	1,499	3,065	2,995
General and administrative
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 238	$ 481	$ 502	$ 901