Line of Business Information - Summary of Line of Business (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Servicing fees	$ 1,301	$ 1,272	$ 3,860	$ 3,775
Management fees	455	445	1,329	1,306
Foreign exchange trading services	294	284	1,097	837
Securities finance	84	116	268	360
Software and processing fees	172	142	529	501
Total fee revenue	2,306	2,259	7,083	6,779
Net interest income	478	644	1,701	1,930
Total other income	0	0	2	(1)
Total revenue	2,784	2,903	8,786	8,708
Provision for credit losses	0	2	88	7
Total expenses	2,103	2,180	6,440	6,627
Income before income tax expense	$ 681	$ 721	$ 2,258	$ 2,074
Pre-tax margin	24.00%	25.00%	26.00%	24.00%
Operating Segments | Investment Servicing
Segment Reporting Information [Line Items]
Servicing fees	$ 1,301	$ 1,272	$ 3,860	$ 3,775
Management fees	0	0	0	0
Foreign exchange trading services	252	249	998	735
Securities finance	81	114	258	353
Software and processing fees	162	140	528	483
Total fee revenue	1,796	1,775	5,644	5,346
Net interest income	482	649	1,716	1,951
Total other income			2	(1)
Total revenue	2,278	2,424	7,362	7,296
Provision for credit losses	0	2	88	7
Total expenses	1,739	1,762	5,315	5,391
Income before income tax expense	$ 539	$ 660	$ 1,959	$ 1,898
Pre-tax margin	24.00%	27.00%	27.00%	26.00%
Operating Segments | Investment Management
Segment Reporting Information [Line Items]
Servicing fees	$ 0	$ 0	$ 0	$ 0
Management fees	455	445	1,329	1,306
Foreign exchange trading services	42	35	99	102
Securities finance	3	2	10	7
Software and processing fees	10	2	1	18
Total fee revenue	510	484	1,439	1,433
Net interest income	(4)	(5)	(15)	(21)
Total other income			0	0
Total revenue	506	479	1,424	1,412
Provision for credit losses	0	0	0	0
Total expenses	358	373	1,096	1,156
Income before income tax expense	$ 148	$ 106	$ 328	$ 256
Pre-tax margin	29.00%	22.00%	23.00%	18.00%
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			0	0
Total revenue	0	0	0	0
Provision for credit losses	0	0	0	0
Total expenses	6	45	29	80
Income before income tax expense	$ (6)	$ (45)	$ (29)	$ (80)