Capitalized Software, Furniture, Equipment and Leasehold Improvements - Capitalized Software Development Costs, Furniture, Equipment and Leasehold Improvements, Net of Accumulated Depreciation and Amortization (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Furniture, equipment, leasehold improvements and capitalized software, Gross	$ 88,674	$ 76,818
Accumulated depreciation and amortization	(56,489)	(44,115)
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	32,185	32,703
Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Furniture, equipment, leasehold improvements and capitalized software, Gross	50,327	41,062
Computer Hardware and Related Software [Member]
Property, Plant and Equipment [Line Items]
Furniture, equipment, leasehold improvements and capitalized software, Gross	24,095	22,051
Office Hardware [Member]
Property, Plant and Equipment [Line Items]
Furniture, equipment, leasehold improvements and capitalized software, Gross	2,785	2,380
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Furniture, equipment, leasehold improvements and capitalized software, Gross	1,921	1,777
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Furniture, equipment, leasehold improvements and capitalized software, Gross	8,128	8,129
Computer Hardware Under Capital Lease [Member]
Property, Plant and Equipment [Line Items]
Furniture, equipment, leasehold improvements and capitalized software, Gross	$ 1,418	$ 1,419