Income Taxes - Summary of Reconciliation of Gross Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Unrecognized Tax Benefits [Line Items]
Beginning balance	$ 33,000	$ 21,142	$ 21,965
Additions based on tax positions related to prior years	4,195	13,366	732
Settlements with taxing authorities	(5,038)
Reductions due to expiration of statute of limitations	(1,105)	(1,508)	(1,555)
Ending balance	$ 31,052	$ 33,000	$ 21,142