Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 53,677	$ 47,316
Less: accumulated depreciation and amortization	(23,521)	(18,359)
Property and equipment, net	30,156	28,957
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	27,672	24,242
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	15,295	13,004
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,321	5,150
Computer software purchased
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,750	3,750
Computer software developed for internal use
Property, Plant and Equipment [Line Items]
Property and equipment, gross	721	721
Fixed assets in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 918	$ 449