Component of Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Leasehold Improvements	Dec. 31, 2012 Furniture and Fixtures	Dec. 31, 2012 Office Equipment	Dec. 31, 2012 Purchased Computer Software	Dec. 31, 2012 Computer Hardware	Dec. 31, 2012 Building
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			9 years	7 years	7 years	3 years	3 years	50 years
Computer hardware	$ 24,239	$ 19,145
Leasehold improvements	5,527	4,107
Purchased computer software	4,452	2,653
Furniture and fixtures	4,351	3,789
Office equipment	4,325	3,646
Building	16,534	16,534
Construction in progress (Note 17)	15,561	1,545
Property, Plant and Equipment, Gross, Total	74,989	51,419
Less accumulated depreciation and amortization	(21,854)	(15,937)
Property plant equipment, net	$ 53,135	$ 35,482