Income Taxes (Components Of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current (benefit) expense:
Federal and state		$ (111.9)	$ 240.1	$ 40.6
Foreign		41.0	18.1	22.9
Total current (benefit) expense		(70.9)	258.2	63.5
Deferred (benefit) expense:
Federal and state		8.7	19.6	0.2
Foreign		(12.9)	5.4	(4.1)
Total deferred (benefit) expense	[1]	(4.2)	25.0	(3.9)
Total income tax (benefit) expense		$ (75.1)	$ 283.2	$ 59.6

[1] 2017 includes the one-time $177.0 million benefit from the reduction of net deferred tax liabilities following the enactment of the U.S. Tax Cuts and Jobs Act. Refer to Note 9 - Income Taxes, for more information.