Earnings per Common Share (Schedule of Basic and Diluted Earnings per Common Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 213	$ 247
Dividends, Preferred Stock, Cash	0	(15)
Net income (loss) from continuing operations attributable to common shareholders	213	232
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	1	3
Net Income (Loss) Available to Common Stockholders, Basic	$ 214	$ 235
Weighted Average Number of Shares Outstanding, Basic	465,961,123	484,233,246
Weighted Average Number of Shares Outstanding, Diluted	466,829,404	484,654,229
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.46	$ 0.48
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0.00	0.01
Earnings Per Share, Basic	0.46	0.49
Earnings Per Share, Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Diluted Share	0.46	0.48
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0.00	0.01
Earnings Per Share, Diluted	$ 0.46	$ 0.49