Earnings Per Common Share (EPS) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic and diluted:
Net income	$ 1,266	$ 1,477	$ 4,264	$ 4,438
Preferred Dividends	(22)	0	(42)	0
Net income available to common shareholders, basic	1,244	1,477	4,222	4,438
Net income available to common shareholders, diluted	1,244	1,477	4,222	4,438
Earnings allocated to participating share awards	(10)	(11)	(32)	(35)
Net income attributable to common shareholders	$ 1,234	$ 1,466	$ 4,190	$ 4,403
Denominator:
Basic	994,000,000	1,041,000,000	1,007,000,000	1,051,000,000
Add: Weighted-average stock options	3,000,000	6,000,000	4,000,000	6,000,000
Diluted	997,000,000	1,047,000,000	1,011,000,000	1,057,000,000
Earnings Per Common Share, Basic [Abstract]
Income from continuing operations attributable to common shareholders	$ 1.24	$ 1.41	$ 4.16	$ 4.19
Earnings Per Common Share, Diluted [Abstract]
Income from continuing operations attributable to common shareholders	$ 1.24	$ 1.4	$ 4.15	$ 4.17
Stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per Share, amount	600,000	200,000	500,000	200,000