Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income tax expense	$ 8,723	$ 8,266	$ 29,366	$ 31,221
Estimated effective tax rates	38.30%	38.20%	37.90%	38.40%