Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Income Tax [Line Items]
Income tax examination, increase (decrease) in liability from prior year			$ 10.9
Unrecognized tax benefits related to federal, state and foreign taxes	$ 30.3	$ 36.1
Unrecognized tax benefits that would impact effective tax rate	27.3
Accrued interest	2.9	$ 2.9
Decrease in unrecognized tax benefits within the next 12 months	$ 8.5
Number of months unrecognized tax benefits may decrease	12 months