Income Tax - Summary of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits, Excluding Interest and Penalties (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Contingency [Line Items]
Balance, beginning of period	$ (41,241)	$ (45,936)	$ (27,008)
Additions for current year tax positions	(6,790)	(900)	(3,164)
Additions for prior year tax positions	(2,610)		(15,764)
Reductions for prior year tax positions	2,288	1,851
Reductions related to statute of limitation expirations		3,744
Balance, end of period	$ (48,353)	$ (41,241)	$ (45,936)