Net Revenues and Long Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues	[1]	$ 253,636	$ 228,332	$ 714,032	$ 676,105
Long-lived assets	[2]	108,210		108,210		$ 109,957
North America
Segment Reporting Information [Line Items]
Net revenues	[1],[3]	229,312	207,541	645,121	614,921
Long-lived assets	[2],[3]	3,477		3,477		2,645
India
Segment Reporting Information [Line Items]
Net revenues	[1]	1,156	589	2,624	1,505
Long-lived assets	[2]	103,556		103,556		105,949
Europe
Segment Reporting Information [Line Items]
Net revenues	[1],[4]	22,672	19,146	64,225	56,635
Long-lived assets	[2],[4]	60		60		71
Rest of the World
Segment Reporting Information [Line Items]
Net revenues	[1]	496	$ 1,056	2,062	$ 3,044
Long-lived assets	[2]	$ 1,117		$ 1,117		$ 1,292

[1] Net revenues are attributed to regions based upon customer location.

[2] Long-lived assets include property and equipment, net of accumulated depreciation and amortization, and goodwill.

[3] Primarily relates to operations in the United States.

[4] Primarily relates to operations in the United Kingdom.