Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 1,374	$ 1,356	$ 2,645	$ 2,595
Net income attributable to noncontrolling interests	12	10	22	20
Preferred stock dividends	55	55	118	118
Preferred stock discount accretion and redemptions	1	1	2	2
Net income attributable to common shares	1,306	1,290	2,503	2,455
Less: Dividends and undistributed earnings allocated to participating securities	4	5	9	10
Net income attributable to basic common shares	$ 1,302	$ 1,285	$ 2,494	$ 2,445
Basic weighted-average common shares outstanding (in shares)	451	469	453	471
Basic earnings per common share (in dollars per share)	$ 2.89	$ 2.74	$ 5.51	$ 5.19
Less: Impact of BlackRock earnings per share dilution	$ 2	$ 3	$ 5	$ 5
Net income attributable to diluted common shares	$ 1,300	$ 1,282	$ 2,489	$ 2,440
Dilutive potential common shares (in shares)	1	3	1	3
Diluted weighted-average common shares outstanding (in shares)	452	472	454	474
Diluted earnings per common share (in dollars per share)	$ 2.88	$ 2.72	$ 5.49	$ 5.15