Net Income Per Common Share (Details) (USD $) In Millions	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Sep. 30, 2008	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2009
Basic:
Income from continuing operations	$ 161.4	$ 41.6		$ 317.2	$ 160.2
Income from discontinued operations			16.6	190.3		25.5
Net income applicable to common stock	161.4	41.6		507.5	160.2
Weighted average common shares outstanding	165.4	167.8		165.2	167.7
Diluted:
Income from continuing operations	161.4	41.6		317.2	160.2
Income from discontinued operations			16.6	190.3		25.5
Net income applicable to common stock	$ 161.4	$ 41.6		$ 507.5	$ 160.2
Weighted average common shares outstanding	165.4	167.8		165.2	167.7
Incremental shares from assumed conversions:
Options, performance-based stock awards and other employee awards	2.3	1.9		2.5	1.9
Weighted average common shares and common share equivalents	167.7	169.7		167.7	169.6