Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 1,392	$ 1,400	$ 4,037	$ 3,995
Net income attributable to noncontrolling interests	13	11	35	31
Preferred stock dividends	63	63	181	181
Preferred stock discount accretion and redemptions	1	1	3	3
Net income attributable to common shareholders	1,315	1,325	3,818	3,780
Less: Dividends and undistributed earnings allocated to participating securities	6	6	15	16
Net income attributable to basic common shares	$ 1,309	$ 1,319	$ 3,803	$ 3,764
Basic weighted-average common shares outstanding (in shares)	444	465	450	469
Basic earnings per common share (in dollars per share)	$ 2.95	$ 2.84	$ 8.45	$ 8.03
Less: Impact of BlackRock earnings per share dilution	$ 2	$ 2	$ 7	$ 7
Net income attributable to diluted common shares	$ 1,307	$ 1,317	$ 3,796	$ 3,757
Dilutive potential common shares (in shares)	1	2	1	3
Diluted weighted-average common shares outstanding (in shares)	445	467	451	472
Diluted earnings per common share (in dollars per share)	$ 2.94	$ 2.82	$ 8.42	$ 7.96