Income Taxes (Summary Of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ (34.2)	$ (37.0)	$ (6.3)
Additions based on tax positions related to the current year	(1.0)	(1.0)	(30.7)
Reductions based on tax positions related to the current year	0.0	0.0	0.1
Additions for tax positions of prior years	(0.3)	(1.4)	(2.1)
Reductions for tax positions of prior years	28.2	3.8	0.4
Lapses	0.6	1.4	1.6
Balance at end of year	$ (6.7)	$ (34.2)	$ (37.0)