Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate	39.80%	55.80%	41.60%	43.50%
Liability for unrecognized tax benefit	$ 6.2		$ 6.2		$ 6.7
Unrecognized tax benefit highly certain	$ 3.8		$ 3.8