Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate	41.20%	41.10%	42.70%	40.90%
Liability for unrecognized tax benefit	$ 6.0		$ 6.0		$ 6.7
Unrecognized tax benefit highly certain	$ 3.6		$ 3.6