Income Taxes (Additional Information) (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 29,769,000	$ 25,828,000	$ 59,443,000	$ 49,962,000
Effective tax rate	29.30%	29.20%	28.90%	28.70%
Reasonably possible change in unrecognized tax benefits over next 12 months, lower range	0		0
Reasonably possible change in unrecognized tax benefits over next 12 months, upper range	$ 1,000,000		$ 1,000,000