Computation of Earnings (Loss) Per Basic/Diluted Common 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
Numerator:
Consolidated net income (loss)	$ 204	$ 324	$ 497	$ 780
Less: Distributed earnings to unvested share-based awards that participate in earnings	0	0	(5)	(4)
Less: Undistributed earnings allocated to unvested share-based awards that participate in earnings	(4)	(6)	(8)	(12)
Numerator for basic earnings per common share-income (loss) available to common shareholders	$ 200	$ 318	$ 484	$ 764
Denominator:
Denominator for basic earnings per common share - weighted-average common shares outstanding (in shares)	716	1,118	712	1,116
Effect of potential dilutive common shares under the treasury stock method:
Employee stock options and others (in shares)	9	9	11	8
Denominator for diluted earnings per common share - weighted-average common shares outstanding plus dilutive effect of employee stock options and others (in shares)	725	1,127	723	1,124
Basic earnings per common share (in dollars per share)	$ 0.28	$ 0.28	$ 0.68	$ 0.68
Diluted earnings per common share (in dollars per share)	$ 0.28	$ 0.28	$ 0.67	$ 0.68
Common stock weighted-average shares, unvested restricted stock rights (in shares)	16	24	16	25
Options
Antidilutive [Line Items]
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	2	8	3	9
Restricted Stocks
Antidilutive [Line Items]
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	3		3