Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Company's effective tax rate	30.50%	27.00%	29.40%	27.40%
Federal statutory income tax rate	35.00%
Unrecognized Tax Benefits, Period Increase (Decrease)	$ 1.5		$ 2.7
Increase In Unrecognized Tax Benefits That Would Impact Effective Tax Rate	1.4		2.6
Recognized interest expense related to unrecognized tax benefits	0.1		0.5
Interest and penalty related to unrecognized tax benefits recorded	6.7		6.7		$ 6.2
Reasonable possible increase in unrecognized tax benefits during the next twelve months	$ (6.2)		$ (6.2)