Exit and Other Related Liabilities (Summary of the Activity in Exit Liabilities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Restructuring Reserve
Balance at December 31, 2019	$ 0
Exit and other related liabilities assumed in business acquisition	23
Costs incurred and charged to expense	176
Costs paid or otherwise settled	(89)
Balance at December 31, 2020	110
Investor Services [Member] | Employee Compensation and Benefits [Member]
Restructuring Reserve
Balance at December 31, 2019	0
Exit and other related liabilities assumed in business acquisition	18
Costs incurred and charged to expense	138
Costs paid or otherwise settled	(70)
Balance at December 31, 2020	86
Advisor Services [Member] | Employee Compensation and Benefits [Member]
Restructuring Reserve
Balance at December 31, 2019	0
Exit and other related liabilities assumed in business acquisition	5
Costs incurred and charged to expense	38
Costs paid or otherwise settled	(19)
Balance at December 31, 2020	$ 24