Net Property and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 135,046	$ 120,914
Less: accumulated depreciation and amortization	(74,416)	(60,554)
Property and equipment, net	60,630	60,360
Computer and office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 92,237	81,850
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant & equipment useful lives	Lesser of useful life of improvement or remaining life of lease
Property and equipment, gross	$ 19,380	17,193
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant & equipment useful lives	7 years
Property and equipment, gross	$ 11,304	11,202
Building and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 10,340	8,884
Land
Property, Plant and Equipment [Line Items]
Property, plant & equipment useful lives	Non depreciable
Property and equipment, gross	$ 1,785	$ 1,785
Minimum | Computer and office equipment
Property, Plant and Equipment [Line Items]
Property, plant & equipment useful lives	3 years
Minimum | Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant & equipment useful lives	7 years
Maximum | Computer and office equipment
Property, Plant and Equipment [Line Items]
Property, plant & equipment useful lives	5 years
Maximum | Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant & equipment useful lives	30 years