Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Taxes [Line Items]
Effective income tax rate	33.40%	26.80%	30.70%	27.50%
Increase/(decrease) in effective tax rate due to impact of discrete tax items	3.30%	1.10%	3.60%	(0.20%)
Net increase to income tax reserves for unrecognized tax benefits based on tax positions related to current and prior years	$ 0.9
Adjustment to income tax reserves for unrecognized tax benefits of prior years due to lapse of applicable statute of limitations	8.7
Unrecognized tax benefits reserve that would impact effective tax rate if released into income	26.9		$ 26.9
Current Tax Payable Part of Other Current Liabilities
Income Taxes [Line Items]
Unrecognized tax benefits reserve that would impact effective tax rate if released into income	1.9		1.9
Non-Current Tax Payable Part of Other Non-current Liabilities
Income Taxes [Line Items]
Unrecognized tax benefits reserve that would impact effective tax rate if released into income	$ 25.0		$ 25.0