Line of Business Information - Summary of Line of Business (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Segment Reporting Information [Line Items]
Servicing fees	$ 1,409	$ 1,275
Management fees	724	587
Foreign exchange trading services	435	337
Securities finance	116	114
Software services	169	158
Other fee revenue	107	99
Total fee revenue	2,960	2,570
Net interest income	835	714
Total other income	1	0
Total revenue	3,796	3,284
Provision for credit losses	16	12
Compensation and employee benefits expenses	1,441	1,262
Information systems and communications	637	497
Transaction processing services	283	258
Other	450	433
Total expenses	2,811	2,450
Income before income tax expense	$ 969	$ 822
Pre-tax margin	26.00%	25.00%
Average assets (in billions)	$ 351,700	$ 337,300
Operating Segments | Investment Servicing
Segment Reporting Information [Line Items]
Servicing fees	1,409	1,275
Foreign exchange trading services	432	337
Securities finance	110	108
Software services	169	158
Other fee revenue	102	101
Total fee revenue	2,222	1,979
Net interest income	832	709
Total other income	1	0
Total revenue	3,055	2,688
Provision for credit losses	16	12
Compensation and employee benefits expenses	1,187	1,103
Information systems and communications	558	477
Transaction processing services	230	216
Other	214	223
Total expenses	2,189	2,019
Income before income tax expense	$ 850	$ 657
Pre-tax margin	28.00%	24.00%
Average assets (in billions)	$ 347,800	$ 333,900
Operating Segments | Investment Management
Segment Reporting Information [Line Items]
Servicing fees	0	0
Management fees	724	587
Foreign exchange trading services	3	0
Securities finance	6	6
Software services	0	0
Other fee revenue	5	(2)
Total fee revenue	738	591
Net interest income	3	5
Total other income	0	0
Total revenue	741	596
Provision for credit losses	0	0
Compensation and employee benefits expenses	175	159
Information systems and communications	29	20
Transaction processing services	53	42
Other	235	210
Total expenses	492	431
Income before income tax expense	$ 249	$ 165
Pre-tax margin	34.00%	28.00%
Average assets (in billions)	$ 3,900	$ 3,400
Other
Segment Reporting Information [Line Items]
Servicing fees	0	0
Management fees	0	0
Foreign exchange trading services	0	0
Securities finance	0	0
Software services	0	0
Other fee revenue	0	0
Total fee revenue	0	0
Net interest income	0	0
Total other income	0	0
Total revenue	0	0
Provision for credit losses	0	0
Compensation and employee benefits expenses	79	0
Information systems and communications	50	0
Transaction processing services	0	0
Other	1	0
Total expenses	130	0
Income before income tax expense	$ (130)	$ 0