Income per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations Attributable to Parent	$ (386)	$ 360	$ (662)	$ 758
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	180	0	931
Net income (loss)	$ (386)	$ 540	$ (662)	$ 1,689
Weighted average common shares outstanding, basic	677	676	676	684
Effect of dilutive securities	0	3	0	4
Weighted average common shares outstanding, diluted	677	679	676	688
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	13	5	13	4
Basic:
Income (loss) from continuing operations per basic share	$ (0.57)	$ 0.53	$ (0.98)	$ 1.11
Discontinued operations per basic share	0.00	0.27	0.00	1.36
Net income (loss), per basic share	(0.57)	0.80	(0.98)	2.47
Diluted:
Income (loss) from continuing operations per diluted share	(0.57)	0.53	(0.98)	1.10
Discontinued operations per diluted share	0.00	0.27	0.00	1.36
Net income (loss), per diluted share	$ (0.57)	$ 0.80	$ (0.98)	$ 2.46