Income per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations Attributable to Parent	$ (749)	$ 304	$ (1,411)	$ 1,062
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	127	0	1,058
Net income (loss)	$ (749)	$ 431	$ (1,411)	$ 2,120
Weighted average common shares outstanding, basic	677	675	677	681
Effect of dilutive securities	0	3	0	3
Weighted average common shares outstanding, diluted	677	678	677	684
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	13	2	13	4
Basic:
Income (loss) from continuing operations per basic share	$ (1.11)	$ 0.45	$ (2.09)	$ 1.56
Discontinued operations per basic share	0.00	0.19	0.00	1.55
Net income (loss), per basic share	(1.11)	0.64	(2.09)	3.11
Diluted:
Income (loss) from continuing operations per diluted share	(1.11)	0.45	(2.09)	1.55
Discontinued operations per diluted share	0.00	0.19	0.00	1.55
Net income (loss), per diluted share	$ (1.11)	$ 0.64	$ (2.09)	$ 3.10