Line of Business Information - Summary of Line of Business (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [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	0	53	2
Total revenue	3,034	2,937	5,984	6,002
Provision for credit losses	(15)	52	(24)	88
Total expenses	2,111	2,082	4,443	4,337
Income before income taxes	$ 938	$ 803	$ 1,565	$ 1,577
Pre-tax margin	31.00%	27.00%	26.00%	26.00%
Operating Segments | Investment Servicing
Segment Reporting Information [Line Items]
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 other income	0	0	0	2
Total revenue	2,452	2,472	4,896	5,084
Provision for credit losses	(15)	52	(24)	88
Total expenses	1,755	1,717	3,634	3,576
Income before income taxes	$ 712	$ 703	$ 1,286	$ 1,420
Pre-tax margin	29.00%	28.00%	26.00%	28.00%
Operating Segments | Investment Management
Segment Reporting Information [Line Items]
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 other income	0	0	0	0
Total revenue	529	465	1,035	918
Provision for credit losses	0	0	0	0
Total expenses	346	353	743	738
Income before income taxes	$ 183	$ 112	$ 292	$ 180
Pre-tax margin	35.00%	24.00%	28.00%	20.00%
Other
Segment Reporting Information [Line Items]
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 other income	53	0	53	0
Total revenue	53	0	53	0
Provision for credit losses	0	0	0	0
Total expenses	10	12	66	23
Income before income taxes	$ 43	$ (12)	$ (13)	$ (23)