Contract revenue - Disaggregation of Contract Revenues (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
Disaggregation of Revenue [Line Items]
Total fee and other revenue	$ 3,117	$ 3,176	$ 3,128	$ 9,625	$ 9,272
Income from consolidated investment management funds, net of noncontrolling interests	937	950	1,038	2,867	3,001
Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,905	2,876	2,902	8,746	8,538
Fee and other revenue - not in scope of ASC 606	232	339	226	918	756
Total fee and other revenue	3,137	3,215	3,128	9,664	9,294
Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,155	1,157	1,121	3,451	3,323
Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	397	431	419	1,298	1,227
Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	296	277	324	836	866
Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	152	145	140	446	413
Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,000	2,010	2,004	6,031	5,829
Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	839	791	829	2,493	2,503
Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	15	24	14	67	48
Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	29	27	33	87	95
Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	22	24	22	68	63
Investment Services | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,061	2,081	2,067	6,244	6,018
Fee and other revenue - not in scope of ASC 606	185	258	229	777	672
Total fee and other revenue	2,246	2,339	2,296	7,021	6,690
Investment Services | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,143	1,147	1,106	3,417	3,282
Investment Services | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	397	431	419	1,298	1,228
Investment Services | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	296	277	324	836	866
Investment Services | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	153	144	140	446	412
Investment Services | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,989	1,999	1,989	5,997	5,788
Investment Services | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	4	4	4	13	12
Investment Services | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	13	23	14	64	47
Investment Services | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(2)	(7)	(12)	(21)	(39)
Investment Services | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	57	62	72	191	210
Investment and Wealth Management | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	863	811	844	2,552	2,551
Fee and other revenue - not in scope of ASC 606	8	27	(6)	3	10
Total fee and other revenue	871	838	838	2,555	2,561
Income from consolidated investment management funds, net of noncontrolling interests	20	39	0	39	22
Investment and Wealth Management | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	25	25	20	73	60
Investment and Wealth Management | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Investment and Wealth Management | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Investment and Wealth Management | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1	0	0	1	1
Investment and Wealth Management | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	26	25	20	74	61
Investment and Wealth Management | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	838	792	829	2,492	2,503
Investment and Wealth Management | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1	1	0	2	0
Investment and Wealth Management | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	31	34	45	108	134
Investment and Wealth Management | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(33)	(41)	(50)	(124)	(147)
Other | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(19)	(16)	(9)	(50)	(31)
Fee and other revenue - not in scope of ASC 606	39	54	3	138	74
Total fee and other revenue	20	38	(6)	88	43
Other | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(13)	(15)	(5)	(39)	(19)
Other | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	(1)
Other | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Other | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(2)	1	0	(1)	0
Other | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(15)	(14)	(5)	(40)	(20)
Other | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(3)	(5)	(4)	(12)	(12)
Other | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1	0	0	1	1
Other | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Other | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	$ (2)	$ 3	$ 0	$ 1	$ 0