Revenue from Contracts with Customers - Revenue by Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total revenue	$ 3,796	$ 3,284
Total revenue
Disaggregation of Revenue [Line Items]
Total revenue	3,796	3,284
Total fee revenue
Disaggregation of Revenue [Line Items]
Total revenue	2,960	2,570
Servicing fees
Disaggregation of Revenue [Line Items]
Total revenue	1,409	1,275
Management fees
Disaggregation of Revenue [Line Items]
Total revenue	724	587
Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Total revenue	435	337
Securities finance
Disaggregation of Revenue [Line Items]
Total revenue	116	114
Software services
Disaggregation of Revenue [Line Items]
Total revenue	169	158
Other fee revenue
Disaggregation of Revenue [Line Items]
Total revenue	107	99
Net interest income
Disaggregation of Revenue [Line Items]
Total revenue	835	714
Total other income
Disaggregation of Revenue [Line Items]
Total revenue	1
Operating Segments | Investment Servicing
Disaggregation of Revenue [Line Items]
Total revenue	3,055	2,688
Operating Segments | Investment Servicing | Total revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,744	1,578
All other revenue	1,311	1,110
Total revenue	3,055	2,688
Operating Segments | Investment Servicing | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,744	1,578
All other revenue	478	401
Total revenue	2,222	1,979
Operating Segments | Investment Servicing | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	1,409	1,275
All other revenue	0	0
Total revenue	1,409	1,275
Operating Segments | Investment Servicing | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Operating Segments | Investment Servicing | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	111	100
All other revenue	321	237
Total revenue	432	337
Operating Segments | Investment Servicing | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	55	45
All other revenue	55	63
Total revenue	110	108
Operating Segments | Investment Servicing | Software services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	169	158
All other revenue	0	0
Total revenue	169	158
Operating Segments | Investment Servicing | Other fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	102	101
Total revenue	102	101
Operating Segments | Investment Servicing | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	832	709
Total revenue	832	709
Operating Segments | Investment Servicing | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0
All other revenue	1
Total revenue	1
Operating Segments | Investment Management
Disaggregation of Revenue [Line Items]
Total revenue	741	596
Operating Segments | Investment Management | Total revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	727	587
All other revenue	14	9
Total revenue	741	596
Operating Segments | Investment Management | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	727	587
All other revenue	11	4
Total revenue	738	591
Operating Segments | Investment Management | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Operating Segments | Investment Management | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	724	587
All other revenue	0	0
Total revenue	724	587
Operating Segments | Investment Management | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	3	0
All other revenue	0	0
Total revenue	3	0
Operating Segments | Investment Management | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	6	6
Total revenue	6	6
Operating Segments | Investment Management | Software services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Operating Segments | Investment Management | Other fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	5	(2)
Total revenue	5	(2)
Operating Segments | Investment Management | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	3	5
Total revenue	3	5
Operating Segments | Investment Management | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0
All other revenue	0
Total revenue	0
Other
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Other | Total revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Total fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Servicing fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Management fees
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Foreign exchange trading services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Securities finance
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Software services
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Other fee revenue
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	0
Other | Net interest income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0	0
All other revenue	0	0
Total revenue	0	$ 0
Other | Total other income
Disaggregation of Revenue [Line Items]
Topic 606 revenue	0
All other revenue	0
Total revenue	$ 0