Contract revenue - Disaggregation of Contract Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total fee and other revenue	$ 3,332	$ 3,946	$ 3,032
Income from consolidated investment management funds, net of noncontrolling interests	980	1,440	946
Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,965	2,916	2,783
Fee and other revenue - not in scope of ASC 606	347	1,038	265
Total fee and other revenue	3,312	3,954	3,048
Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,139	1,128	1,093
Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	470	421	398
Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	263	264	251
Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	149	148	132
Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,021	1,961	1,874
Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	863	887	841
Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	28	12	17
Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	31	34	31
Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	22	22	20
Investment Services | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,102	2,029	1,938
Fee and other revenue - not in scope of ASC 606	334	207	223
Total fee and other revenue	2,436	2,236	2,161
Investment Services | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,127	1,117	1,081
Investment Services | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	470	421	398
Investment Services | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	263	264	251
Investment Services | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	149	148	132
Investment Services | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,009	1,950	1,862
Investment Services | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	5	5	4
Investment Services | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	28	12	17
Investment Services | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(12)	(10)	(14)
Investment Services | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	72	72	69
Investment Management | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	878	905	857
Fee and other revenue - not in scope of ASC 606	(32)	19	12
Total fee and other revenue	846	924	869
Income from consolidated investment management funds, net of noncontrolling interests	(20)	8	16
Investment Management | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	23	25	20
Investment Management | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Investment Management | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Investment Management | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Investment Management | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	23	25	20
Investment Management | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	862	886	841
Investment Management | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Investment Management | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	43	44	45
Investment Management | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(50)	(50)	(49)
Other | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(15)	(18)	(12)
Fee and other revenue - not in scope of ASC 606	45	812	30
Total fee and other revenue	30	794	18
Other | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(11)	(14)	(8)
Other | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Other | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Other | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Other | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(11)	(14)	(8)
Other | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(4)	(4)	(4)
Other | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Other | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0
Other | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	$ 0	$ 0	$ 0