Goodwill And Intangible Assets (Changes To Intangible Assets) (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Balance at beginning of period, net of accumulated amortization	$ 276.8	$ 282.2
Finite and Indefinite-lived intangible assets acquired	250.8	18.2
Amortization expense	(22.9)	(30.9)
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	(0.1)	7.3
Balance at end of period, net of accumulated amortization	$ 504.6	$ 276.8