Revenue from Contracts with Customers - Disaggregation of Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Servicing fees	$ 1,371	$ 1,287
Management fees	493	464
Foreign exchange trading services	346	444
Securities finance	99	92
Software and processing fees	174	112
Total fee revenue	2,483	2,399
Net interest income	467	664
Total other income	0
Total revenue	2,950	3,065
Total other income	0	2
Operating Segments
Disaggregation of Revenue [Line Items]
Management fees	493
Foreign exchange trading services	13
Securities finance	4
Software and processing fees	2
Net interest income	(6)
Operating Segments | Investment Servicing
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,634	1,551
All other revenue	810	1,061
Servicing fees	1,371	1,287
Management fees	0	0
Foreign exchange trading services	333	434
Securities finance	95	89
Software and processing fees	172	137
Total fee revenue	1,971	1,947
Net interest income	473	663
Total revenue	2,444	2,612
Total other income	0	2
Operating Segments | Investment Servicing | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,371	1,287
All other revenue	0	0
Servicing fees	1,371	1,287
Operating Segments | Investment Servicing | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Management fees	0	0
Operating Segments | Investment Servicing | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	95	100
All other revenue	238	334
Foreign exchange trading services	333	434
Operating Segments | Investment Servicing | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	60	57
All other revenue	35	32
Securities finance	95	89
Operating Segments | Investment Servicing | Processing fees and other
Disaggregation of Revenue [Line Items]
Topic 606 revenue	108	107
All other revenue	64	30
Software and processing fees	172	137
Operating Segments | Investment Servicing | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,634	1,551
All other revenue	337	396
Total fee revenue	1,971	1,947
Operating Segments | Investment Servicing | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	473	663
Net interest income	473	663
Operating Segments | Investment Servicing | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	2
Total other income	0	2
Operating Segments | Investment Management
Disaggregation of Revenue [Line Items]
Topic 606 revenue	506	474
All other revenue	0	(21)
Servicing fees	0	0
Management fees	493	464
Foreign exchange trading services	13	10
Securities finance	4	3
Software and processing fees	2	(25)
Total fee revenue	512	452
Net interest income	(6)	1
Total revenue	506	453
Total other income	0	0
Operating Segments | Investment Management | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Servicing fees	0	0
Operating Segments | Investment Management | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	493	464
All other revenue	0	0
Management fees	493	464
Operating Segments | Investment Management | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	13	10
All other revenue	0	0
Foreign exchange trading services	13	10
Operating Segments | Investment Management | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	4	3
Securities finance	4	3
Operating Segments | Investment Management | Processing fees and other
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	2	(25)
Software and processing fees	2	(25)
Operating Segments | Investment Management | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	506	474
All other revenue	6	(22)
Total fee revenue	512	452
Operating Segments | Investment Management | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	(6)	1
Net interest income	(6)	1
Operating Segments | Investment Management | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total other income	0	0
Other
Disaggregation of Revenue [Line Items]
Servicing fees	0	0
Management fees	0	0
Foreign exchange trading services	0	0
Securities finance	0	0
Software and processing fees	0	0
Total fee revenue	0	0
Net interest income	0	0
Total revenue	0	0
Total other income	$ 0	$ 0