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	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Effective income tax rate	31.30%	29.20%	31.20%	30.40%
Gross liability for uncertain tax positions	$ 10.4		$ 10.4		$ 10.5
Unrecognized tax benefits if recognized that would affect effective tax rate	4.7		4.7		4.7
Accrued interest	1.9		1.9		1.5
Accrued penalties	1.2		1.2		0.9
Unrecognized tax benefits subject to change with in the next 12 months	$ 0.1		$ 0.1