Income Taxes (Difference In Income Tax Expense And Expected Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate	21.00%	35.00%	35.00%
U.S. federal income tax expense at statutory rate	$ 207.3	$ 305.6	$ 276.4
State income taxes, net of federal benefit	30.2	21.5	20.0
Transition tax	1.2	6.5	0.0
Remeasurement of deferred taxes for Tax Act	(11.5)	(30.8)	0.0
Other, net	7.9	(8.3)	(6.1)
Income tax expense	$ 235.1	$ 294.5	$ 290.3
Effective income tax rate	23.80%	33.70%	36.80%