Accounting for Uncertainty in Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Liability for unrecognized tax	$ 8.2
Unrecognized tax favorable impact on effective tax rate	3.6
Accrued interest and penalties applied to uncertain tax positions	$ 3.7	$ 3.3