Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (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 of unrecognized tax benefits at beginning of year	$ 67,615	$ 63,928	$ 64,673
Gross amount of increases in unrecognized tax benefits as a result of positions taken during a prior year	22,031	118	2
Gross amount of decreases in unrecognized tax benefits as a result of positions taken during a prior year	(1,853)	(50)
Gross amount of increases in unrecognized tax benefits as a result of positions taken during the current year	3,854	8,300	4,706
The amounts of decreases in unrecognized benefits relating to settlements with taxing authorities	(48,355)	(2,960)	(4,945)
Reduction in unrecognized tax benefits due to the lapse of applicable statute of limitation	(2,139)	(1,721)	(508)
Balance of unrecognized tax benefits at end of year	$ 41,153	$ 67,615	$ 63,928