Business segments - Contribution of Segments to Overall Profitability (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Total fee and other revenue	$ 3,430	$ 3,228	$ 3,315	$ 6,658	$ 6,581
Net interest revenue (expense)	824	698	645	1,522	1,300
Provision for credit losses	47	2	(86)	49	(169)
Noninterest expense	3,112	3,006	2,778	6,118	5,629
Net income (loss) attributable to noncontrolling interests	(5)	(8)	5	(13)	10
Operating segments
Segment Reporting Information [Line Items]
Total fee and other revenue	3,435	3,236	3,310	6,671	6,571
Net interest revenue (expense)	824	698	645	1,522	1,300
Total revenue	4,259	3,934	3,955	8,193	7,871
Provision for credit losses	47	2	(86)	49	(169)
Noninterest expense	3,112	3,006	2,778	6,118	5,629
Income (loss) before income taxes	$ 1,100	$ 926	$ 1,263	$ 2,026	$ 2,411
Pre-tax operating margin	26.00%	23.00%	32.00%	25.00%	31.00%
Average assets	$ 437,623	$ 440,202	$ 452,329	$ 438,924	$ 456,332
Operating segments | Securities Services
Segment Reporting Information [Line Items]
Total fee and other revenue	1,549	1,403	1,433	2,952	2,864
Net interest revenue (expense)	457	377	354	834	710
Total revenue	2,006	1,780	1,787	3,786	3,574
Provision for credit losses	13	(10)	(58)	3	(108)
Noninterest expense	1,656	1,510	1,400	3,166	2,819
Income (loss) before income taxes	$ 337	$ 280	$ 445	$ 617	$ 863
Pre-tax operating margin	17.00%	16.00%	25.00%	16.00%	24.00%
Average assets	$ 219,797	$ 220,889	$ 231,152	$ 220,340	$ 229,620
Operating segments | Market and Wealth Services
Segment Reporting Information [Line Items]
Total fee and other revenue	974	906	903	1,880	1,817
Net interest revenue (expense)	340	296	289	636	578
Total revenue	1,314	1,202	1,192	2,516	2,395
Provision for credit losses	4	(2)	(19)	2	(48)
Noninterest expense	702	708	652	1,410	1,334
Income (loss) before income taxes	$ 608	$ 496	$ 559	$ 1,104	$ 1,109
Pre-tax operating margin	46.00%	41.00%	47.00%	44.00%	46.00%
Average assets	$ 141,952	$ 141,183	$ 144,297	$ 141,570	$ 146,546
Operating segments | Investment and Wealth Management
Segment Reporting Information [Line Items]
Total fee and other revenue	837	907	952	1,744	1,895
Net interest revenue (expense)	62	57	47	119	95
Total revenue	899	964	999	1,863	1,990
Provision for credit losses	0	(3)	(4)	(3)	0
Noninterest expense	691	755	677	1,446	1,386
Income (loss) before income taxes	$ 208	$ 212	$ 326	$ 420	$ 604
Pre-tax operating margin	23.00%	22.00%	33.00%	23.00%	30.00%
Average assets	$ 33,668	$ 35,629	$ 30,370	$ 34,643	$ 31,213
Net income (loss) attributable to noncontrolling interests	(5)	(8)	5	(13)	10
Operating segments | Other
Segment Reporting Information [Line Items]
Total fee and other revenue	75	20	22	95	(5)
Net interest revenue (expense)	(35)	(32)	(45)	(67)	(83)
Total revenue	40	(12)	(23)	28	(88)
Provision for credit losses	30	17	(5)	47	(13)
Noninterest expense	63	33	49	96	90
Income (loss) before income taxes	(53)	(62)	(67)	(115)	(165)
Average assets	$ 42,206	$ 42,501	$ 46,510	$ 42,371	$ 48,953