Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 5,346	$ 5,388	$ 3,985
Net income attributable to noncontrolling interests	45	50	82
Preferred stock dividends	236	236	209
Preferred discount accretion and redemptions	4	26	6
Net income attributable to common shares	5,061	5,076	3,688
Less: Dividends and undistributed earnings allocated to participating securities	21	23	26
Net income attributable to basic common shares	5,040	5,053	3,662
Less: Impact of BlackRock earnings per share dilution	9	16	12
Net income attributable to diluted common shares	$ 5,031	$ 5,037	$ 3,650
Weighted Average Number of Shares Outstanding, Basic (shares)	467	481	494
Basic earnings per common share (dollars per share)	$ 10.79	$ 10.49	$ 7.42
Dilutive potential common shares	3	5	6
Weighted Average Number of Shares Outstanding, Diluted (shares)	470	486	500
Diluted earnings per common share (dollars per share)	$ 10.71	$ 10.36	$ 7.30