Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 1,356	$ 1,097	$ 2,595	$ 2,171
Net income attributable to noncontrolling interests	10	10	20	27
Preferred stock dividends	55	55	118	118
Preferred stock discount accretion and redemptions	1	2	2	23
Net Income Loss Available To Common Stockholders	1,290	1,030	2,455	2,003
Dividends and undistributed earnings allocated to participating securities	5	4	10	10
Net income attributable to basic common shares	$ 1,285	$ 1,026	$ 2,445	$ 1,993
Basic weighted-average common shares outstanding	469	484	471	486
Basic earnings per common share	$ 2.74	$ 2.12	$ 5.19	$ 4.10
Less: Impact of BlackRock earnings per share dilution	$ 3	$ 1	$ 5	$ 5
Net income attributable to diluted common shares	$ 1,282	$ 1,025	$ 2,440	$ 1,988
Dilutive potential common shares	3	4	3	5
Diluted weighted-average common shares outstanding	472	488	474	491
Diluted earnings per common share	$ 2.72	$ 2.10	$ 5.15	$ 4.05