Income Taxes - Additional Information (Detail) (USD $) In Millions, 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]
Effective income tax rate	32.10%	29.50%	32.60%	29.00%
U.S. federal income tax rate	35.00%	35.00%	35.00%	35.00%
Unrecognized tax benefits	$ 9.5		$ 9.5
Recognized tax benefits	5.1		5.1
Accrued interest and penalties related to uncertain tax positions	$ 0.9		$ 0.9