Revenue from Contracts with Customers - Disaggregation of Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Servicing fees	$ 1,399	$ 1,272	$ 2,770	$ 2,559
Management fees	504	444	997	908
Foreign exchange trading services	286	325	632	769
Securities finance	109	92	208	184
Software and processing fees	216	245	390	357
Total fee revenue	2,514	2,378	4,997	4,777
Net interest income	467	559	934	1,223
Total other income	53			2
Total revenue	3,034	2,937	5,984	6,002
Operating Segments | Investment Servicing
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,699	1,581	3,333	3,132
All other revenue	753	891	1,563	1,952
Servicing fees	1,399	1,272	2,770	2,559
Management fees	0	0	0	0
Foreign exchange trading services	270	312	603	746
Securities finance	106	88	201	177
Software and processing fees	209	229	381	366
Total fee revenue	1,984	1,901	3,955	3,848
Net interest income	468	571	941	1,234
Total revenue	2,452	2,472	4,896	5,084
Operating Segments | Investment Servicing | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,399	1,272	2,770	2,559
All other revenue	0	0	0	0
Servicing fees	1,399	1,272	2,770	2,559
Operating Segments | Investment Servicing | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0	0	0
All other revenue	0	0	0	0
Management fees	0	0	0	0
Operating Segments | Investment Servicing | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	83	95	178	195
All other revenue	187	217	425	551
Foreign exchange trading services	270	312	603	746
Operating Segments | Investment Servicing | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	61	63	121	120
All other revenue	45	25	80	57
Securities finance	106	88	201	177
Operating Segments | Investment Servicing | Processing fees and other
Disaggregation of Revenue [Line Items]
Topic 606 revenue	156	151	264	258
All other revenue	53	78	117	108
Software and processing fees	209	229	381	366
Operating Segments | Investment Servicing | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,699	1,581	3,333	3,132
All other revenue	285	320	622	716
Total fee revenue	1,984	1,901	3,955	3,848
Operating Segments | Investment Servicing | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0	0	0
All other revenue	468	571	941	1,234
Net interest income	468	571	941	1,234
Operating Segments | Investment Servicing | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0	0
All other revenue	0		0	2
Total other income	0		0	2
Operating Segments | Investment Management
Disaggregation of Revenue [Line Items]
Topic 606 revenue	520	457	1,026	931
All other revenue	9	8	9	(13)
Servicing fees	0	0	0	0
Management fees	504	444	997	908
Foreign exchange trading services	16	13	29	23
Securities finance	3	4	7	7
Software and processing fees	7	16	9	(9)
Total fee revenue	530	477	1,042	929
Net interest income	(1)	(12)	(7)	(11)
Total revenue	529	465	1,035	918
Operating Segments | Investment Management | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0	0	0
All other revenue	0	0	0	0
Servicing fees	0	0	0	0
Operating Segments | Investment Management | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	504	444	997	908
All other revenue	0	0	0	0
Management fees	504	444	997	908
Operating Segments | Investment Management | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	16	13	29	23
All other revenue	0	0	0	0
Foreign exchange trading services	16	13	29	23
Operating Segments | Investment Management | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0	0	0
All other revenue	3	4	7	7
Securities finance	3	4	7	7
Operating Segments | Investment Management | Processing fees and other
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0	0	0
All other revenue	7	16	9	(9)
Software and processing fees	7	16	9	(9)
Operating Segments | Investment Management | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	520	457	1,026	931
All other revenue	10	20	16	(2)
Total fee revenue	530	477	1,042	929
Operating Segments | Investment Management | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0	0	0
All other revenue	(1)	(12)	(7)	(11)
Net interest income	(1)	(12)	(7)	(11)
Operating Segments | Investment Management | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0	0
All other revenue	0		0	0
Total other income	0		0	0
Other
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	53		53
Servicing fees	0	0	0	0
Management fees	0	0	0	0
Foreign exchange trading services	0	0	0	0
Securities finance	0	0	0	0
Software and processing fees	0	0	0	0
Total fee revenue	0	0	0	0
Net interest income	0	0	0	0
Total revenue	53	$ 0	53	$ 0
Other | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	0		0
Servicing fees	0		0
Other | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	0		0
Management fees	0		0
Other | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	0		0
Foreign exchange trading services	0		0
Other | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	0		0
Securities finance	0		0
Other | Processing fees and other
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	0		0
Software and processing fees	0		0
Other | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	0		0
Total fee revenue	0		0
Other | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	0		0
Net interest income	0		0
Other | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0		0
All other revenue	53		53
Total other income	$ 53		$ 53