Goodwill And Intangible Assets (Changes To Intangible Assets) (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Finite and Indefinite-lived intangible assets acquired	$ 0.0	$ 252.8
Amortization expense	(20.5)	(44.5)
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	0.9	(3.3)
Balance at end of period, net of accumulated amortization	462.2
Intangible assets, net	$ 462.2	$ 481.8	$ 276.8