Line of Business Information - Summary of Line of Business (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [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	2
Total revenue	2,950	3,065
Provision for credit losses	(9)	36
Total expenses	2,332	2,255
Income before income taxes	$ 627	$ 774
Pre-tax margin	21.00%	25.00%
Operating Segments
Segment Reporting Information [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
Segment Reporting Information [Line Items]
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 other income	0	2
Total revenue	2,444	2,612
Provision for credit losses	(9)	36
Total expenses	1,879	1,859
Income before income taxes	$ 574	$ 717
Pre-tax margin	23.00%	27.00%
Operating Segments | Investment Management
Segment Reporting Information [Line Items]
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 other income	0	0
Total revenue	506	453
Provision for credit losses	0	0
Total expenses	397	385
Income before income taxes	$ 109	$ 68
Pre-tax margin	21.00%	15.00%
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 and processing fees	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
Total expenses	56	11
Income before income taxes	$ (56)	$ (11)