Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Taxes [Line Items]
Provision for income taxes	$ 5,381,000	$ 15,143,000	$ 11,035,000	$ 17,482,000
Net discrete tax benefits	11,200,000	10,500,000	15,200,000	10,500,000
Reasonably possible change to unrecognized tax benefit within the next twelve months, low end of range	185,000,000		185,000,000
Reasonably possible change to unrecognized tax benefit within the next twelve months, high end of range	205,000,000		205,000,000
Unrecognized tax benefits related to settlement of tax audits and/or expiration of statutes of limitations in the next twelve months	$ 9,000,000		$ 9,000,000