Earnings (Loss) Per Common Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Mar. 31, 2012
Document Period End Date		Mar. 31, 2013
Basic
Income from continuing operations, net of tax, available to common shareholders		$ (0.58)	$ 0.20
Income (loss) from discontinued operations, net of tax		$ 0.00	$ 0.00
Net income (loss) available to common shareholders		$ (0.58)	$ 0.20
Diluted
Income from continuing operations, net of tax, available to common shareholders		$ (0.58)	$ 0.19
Income (loss) from discontinued operations, net of tax		$ 0.00	$ (0.01)
Net income available to common shareholders		$ (0.58)	$ 0.18
Shares
Weighted average common shares outstanding, basic		436.3	440.7
Dilutive effect of warrants			26.4
Dilutive effect of stock compensation plans			1.9
Dilutive effect of mandatory convertible preferred shares	21.2
Weighted average shares outstanding and dilutive potential common shares		436.3	469.0
Net income
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ (241)	$ 96
Net income (loss) available to common shareholders		(251)	86
Add: Dilutive effect of preferred stock dividends
Net income (loss) available to common shareholders and assumed conversion of preferred shares		(251)	86
Income (loss) from discontinued operations, net of tax		0	(1)
Income from continuing operations
Income from continuing operations, net of tax		(241)	97
Less: Preferred stock dividends		10	10
Income from continuing operations, net of tax, available to common shareholders		(251)	87
Add: Dilutive effect of preferred stock dividends
Income from continuing operations, net of tax, available to common shareholders and assumed conversion of preferred shares		$ (251)	$ 87