Net Revenues and Long Lived Assets by Geographic Area (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]
Net revenues	$ 228,332	[1]	$ 209,871	[1]	$ 676,105	[1]	$ 601,478	[1]
Long-lived assets	111,735	[2]			111,735	[2]			110,511	[2]
North America
Segment Reporting Information [Line Items]
Net revenues	207,541	[1],[3]	192,751	[1],[3]	614,921	[1],[3]	552,877	[1],[3]
Long-lived assets	2,601	[2],[3]			2,601	[2],[3]			2,713	[2],[3]
India
Segment Reporting Information [Line Items]
Net revenues	589	[1]	314	[1]	1,505	[1]	954	[1]
Long-lived assets	107,723	[2]			107,723	[2]			106,133	[2]
Europe
Segment Reporting Information [Line Items]
Net revenues	19,146	[1],[4]	15,776	[1],[4]	56,635	[1],[4]	43,878	[1],[4]
Long-lived assets	78	[2],[4]			78	[2],[4]			72	[2],[4]
Rest of the World
Segment Reporting Information [Line Items]
Net revenues	1,056	[1]	1,030	[1]	3,044	[1]	3,769	[1]
Long-lived assets	$ 1,333	[2]			$ 1,333	[2]			$ 1,593	[2]

[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.