Income Taxes (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 25,049,000	$ 19,009,000	$ 40,154,000	$ 35,171,000
Effective income tax rate	35.00%	31.40%	32.60%	31.70%
Unrecognized tax benefits	18,400,000		18,400,000		17,600,000
Unrecognized tax benefits reductions resulting from settlements with taxing authorities and lapse of applicable statute of limitations			3,700,000
Liability for uncertain tax positions	$ 14,700,000		$ 14,700,000		$ 13,100,000