Net Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Property and equipment Gross	$ 86,236		$ 57,087
Less: accumulated depreciation and amortization	(44,950)		(36,608)
Property and equipment, net	41,286		20,479
Computer and office equipment
Property, Plant and Equipment [Line Items]
Property and equipment Gross	56,118	[1]	38,295	[1]
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment Gross	13,894		11,493
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment Gross	10,369		7,193
Land and buildings
Property, Plant and Equipment [Line Items]
Property and equipment Gross	5,267
Vehicles and other
Property, Plant and Equipment [Line Items]
Property and equipment Gross	$ 588		$ 106

[1] Includes $4.6 million of computer and office equipment under capital lease for the year ended December 31, 2011.