Goodwill And Intangible Assets (Changes To Intangible Assets) (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Indefinite-lived Intangible Assets Acquired	$ 18.2
Balance at beginning of period, net of accumulated amortization	282.2	$ 317.1
Amortization expense	(22.8)	(30.7)
Balance at end of period, net of accumulated amortization	284.7	282.2
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	$ 7.1	$ (4.2)