Lines of business - Contribution of Segments to Overall Profitability (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019
Segment Reporting Information [Line Items]
Total fee and other revenue	$ 3,117	$ 3,176	$ 3,128	$ 9,625		$ 9,272
Net interest revenue (expense)	703	780	730	2,297		2,373
Provision for credit losses	9	143	(16)	321	[1]	(17)	[1]
Income from consolidated investment management funds, net of noncontrolling interests	937	950	1,038	2,867		3,001
Investment income (loss), net	27	54	3	43		39
Net income (loss) attributable to noncontrolling interests	7	15	3	4		17
Operating segments
Segment Reporting Information [Line Items]
Total fee and other revenue	3,137	3,215	3,128	9,664		9,294
Net interest revenue (expense)	703	780	730	2,297		2,373
Total revenue	3,840	3,995	3,858	11,961		11,667
Provision for credit losses	9	143	(16)	321		(17)
Noninterest expense	2,681	2,686	2,590	8,079		7,936
Income (loss) before taxes	$ 1,150	$ 1,166	$ 1,284	$ 3,561		$ 3,748
Pre-tax operating margin	30.00%	29.00%	33.00%	30.00%		32.00%
Average assets	$ 414,865	$ 415,359	$ 350,679	$ 405,203		$ 343,129
Operating segments | Investment Services
Segment Reporting Information [Line Items]
Total fee and other revenue	2,246	2,339	2,296	7,021		6,690
Net interest revenue (expense)	681	768	761	2,255		2,348
Total revenue	2,927	3,107	3,057	9,276		9,038
Provision for credit losses	(10)	145	(15)	284		(11)
Noninterest expense	2,020	1,989	1,973	5,996		5,917
Income (loss) before taxes	$ 917	$ 973	$ 1,099	$ 2,996		$ 3,132
Pre-tax operating margin	31.00%	31.00%	36.00%	32.00%		35.00%
Average assets	$ 329,324	$ 335,288	$ 269,926	$ 322,924		$ 263,631
Operating segments | Investment and Wealth Management
Segment Reporting Information [Line Items]
Total fee and other revenue	871	838	838	2,555		2,561
Net interest revenue (expense)	47	48	49	147		175
Total revenue	918	886	887	2,702		2,736
Provision for credit losses	12	7	0	28		(1)
Noninterest expense	661	658	592	2,014		1,916
Income (loss) before taxes	$ 245	$ 221	$ 295	$ 660		$ 821
Pre-tax operating margin	27.00%	25.00%	33.00%	24.00%		30.00%
Average assets	$ 30,160	$ 30,327	$ 27,840	$ 30,343		$ 29,815
Income from consolidated investment management funds, net of noncontrolling interests	20	39	0	39		22
Investment income (loss), net	27	54	3	43		39
Net income (loss) attributable to noncontrolling interests	7	15	3	4		17
Operating segments | Other
Segment Reporting Information [Line Items]
Total fee and other revenue	20	38	(6)	88		43
Net interest revenue (expense)	(25)	(36)	(80)	(105)		(150)
Total revenue	(5)	2	(86)	(17)		(107)
Provision for credit losses	7	(9)	(1)	9		(5)
Noninterest expense	0	39	25	69		103
Income (loss) before taxes	(12)	(28)	(110)	(95)		(205)
Average assets	$ 55,381	$ 49,744	$ 52,913	$ 51,936		$ 49,683

[1] In the first quarter of 2020, we adopted new accounting guidance included in ASU 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments, on a prospective basis. See Note 2 of the Notes to Consolidated Financial Statements for additional information.