Earnings Per Share (Reconciliation Of Numerator And Denominator Of Basic EPS With Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings / (Loss)
Income (loss) from continuing operations									$ 259.4	$ (182.6)	$ 724.1
Preferred stock dividends									9.8	0.0	0.0
Income (loss) from continuing operations available to common shareholders	$ (92.6)	$ 222.8	$ 41.2	$ 78.2	$ (425.8)	$ 94.2	$ 88.0	$ 61.0	249.6	(182.6)	724.1
Income (loss) from discontinued operations net of taxes									208.8	(665.4)	310.0
Net income (loss) available to common shareholders	$ (97.8)	$ 219.6	$ 156.7	$ 179.9	$ (1,142.5)	$ 131.5	$ 17.0	$ 146.0	$ 458.4	$ (848.0)	$ 1,034.1
Weighted Average Common Shares Outstanding
Basic shares outstanding (in shares)									162,290	201,850	185,500
Stock-based awards (in shares)									1,660	0	888
Diluted shares outstanding (in shares)									163,950	201,850	186,388
Basic Earnings Per Common Share Data
Income (Loss) from continuing operations (in dollars per share)									$ 1.54	$ (0.90)	$ 3.90
Income (Loss) from discontinued operation (in dollars per share)									1.28	(3.30)	1.67
(Loss) income from discontinued operations, net of taxes (in dollars per share)									2.82	(4.20)	5.57
Diluted Earnings Per Common Share Data
Income (Loss) from continuing operations (in dollars per share)									1.52	(0.90)	3.89
Income (Loss) from discontinued operation (in dollars per share)									1.28	(3.30)	1.66
Diluted (loss) income per common share (in dollars per share)	$ (0.74)	$ 1.61	$ 0.85	$ 0.88	$ (5.65)	$ 0.65	$ 0.08	$ 0.72	$ 2.80	$ (4.20)	$ 5.55
Restricted Shares, Performance Shares, and Out-Of-The Money Options
Diluted Earnings Per Common Share Data
Weighted average shares excluded from diluted earnings per share (in shares)									1,300	2,700	2,000
Restricted Shares, Performance Shares, and Options
Diluted Earnings Per Common Share Data
Weighted average shares excluded from diluted earnings per share (in shares)									700