Acquisitions - Summary of Significant Inputs to Valuation of Contingent Consideration Payable (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2021	Mar. 31, 2022	Dec. 31, 2021
USAA AMCO
Business Acquisition [Line Items]
Non-managed money revenue average annual growth rate		1.00%	5.00%
Market price of risk		6.00%	6.00%
Revenue volatility		16.00%	17.00%
Discount rate		5.00%	3.00%
Years remaining in earn out period		1 year 7 months 6 days	1 year 10 months 24 days
USAA AMCO | Minimum
Business Acquisition [Line Items]
Undiscounted estimated remaining earn out payments in millions		$ 70	$ 72
USAA AMCO | Maximum
Business Acquisition [Line Items]
Undiscounted estimated remaining earn out payments in millions		$ 75	$ 75
WestEnd Acquisition
Business Acquisition [Line Items]
Net revenue average annual growth rate	37.00%	34.00%
Market price of risk	11.00%	11.00%
Revenue volatility	21.00%	20.00%
Discount rate	4.00%	5.00%
Years remaining in earn out period	5 years 9 months 18 days	5 years 7 months 6 days
WestEnd Acquisition | Minimum
Business Acquisition [Line Items]
Undiscounted estimated remaining earn out payments in millions	$ 277	$ 280
WestEnd Acquisition | Maximum
Business Acquisition [Line Items]
Undiscounted estimated remaining earn out payments in millions	$ 320	$ 320