Earnings (Loss) Per Common Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Basic
Income from continuing operations, net of tax, available to common shareholders	$ 0.90	$ 0.11	$ 0.84	$ 1.07
Income (loss) from discontinued operations, net of tax	$ 0.00	$ 0.00	$ (0.01)	$ 0.20
Net income (loss) available to common shareholders	$ 0.90	$ 0.11	$ 0.83	$ 1.27
Diluted
Income from continuing operations, net of tax, available to common shareholders	$ 0.83	$ 0.10	$ 0.79	$ 0.99
Income (loss) from discontinued operations, net of tax	$ 0.00	$ 0.01	$ (0.01)	$ 0.18
Net income available to common shareholders	$ 0.83	$ 0.11	$ 0.78	$ 1.17
Shares
Weighted average common shares outstanding, basic	435.8	445.3	438.2	445.0
Dilutive effect of warrants	23.8	27.4	25.1	34.8
Dilutive effect of stock compensation plans	2.1	0.7	1.9	1.2
Dilutive effect of mandatory convertible preferred shares	21.0			0
Weighted average shares outstanding and dilutive potential common shares	482.7	473.4	465.2	481.0
Net income
Net income (loss)	$ 401	$ 60	$ 396	$ 594
Net income (loss) available to common shareholders	391	50	365	563
Add: Dilutive effect of preferred stock dividends	10
Net income (loss) available to common shareholders and assumed conversion of preferred shares	401	50	365	563
Income (loss) from discontinued operations, net of tax	(2)	3	(4)	85
Income from continuing operations
Income from continuing operations, net of tax	403	57	400	509
Less: Preferred stock dividends	10	10	31	31
Income from continuing operations, net of tax, available to common shareholders	393	47	369	478
Add: Dilutive effect of preferred stock dividends	10
Income from continuing operations, net of tax, available to common shareholders and assumed conversion of preferred shares	403	47	369	478
Income (loss) from continuing operations, net of tax [Member]
Net income
Add: Dilutive effect of preferred stock dividends
Income from continuing operations
Add: Dilutive effect of preferred stock dividends
Net Income [Member]
Net income
Add: Dilutive effect of preferred stock dividends				0
Income from continuing operations
Add: Dilutive effect of preferred stock dividends				$ 0