Common Shareholders' Equity (Earnings Per Share) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Reconciliation of basic and diluted earnings per share of common stock [Abstract]
Income (loss) from continuing operations	$ 492		$ 610		$ 921		$ 652	[1]
Denominator:
Weighted-average number of common shares outstanding - basic (in shares)	434.1		421.8		433.8		421.4
Performance share awards, options, equity units and restricted stock (in shares)	6.0	[2]	3.0	[2]	5.5	[2]	2.9	[2]
Weighted-average number of common shares outstanding - assuming dilution (in shares)	440.1		424.8		439.3		424.3
Earnings per share of common stock from continuing operations:
Basic	$ 1.13		$ 1.45		$ 2.12		$ 1.54
Assuming dilution	$ 1.12		$ 1.44		$ 2.10		$ 1.54
Antidilutive securities (in shares)	0.2		0.3		0.2		0.3

[1] Prior year amounts were restated to conform to current year's presentation. See Note 4 - Nonrecurring Fair Value Measurements

[2] Calculated using the treasury stock method. Performance share awards are included in diluted weighted-average number of common shares outstanding based upon what would be issued if the end of the reporting period was the end of the term of the award.