Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Income Tax [Line Items]
Effective income tax rate	14.10%	19.70%
Income tax examination, increase (decrease) in liability from prior year	$ 2.6	$ 2.6
Unrecognized tax benefits related to federal, state and foreign taxes	21.8	21.8	$ 22.3
Unrecognized tax benefits that would impact effective tax rate	18.2	18.2
Accrued interest	3.3	3.3	$ 2.8
Decrease in unrecognized tax benefits within the next 12 months	$ 3.0	$ 3.0
Number of months unrecognized tax benefits may decrease		12 months