Investments - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2021 USD ($) investment	Dec. 31, 2020 USD ($)	Dec. 31, 2021 USD ($) investment	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity in income of investees	$ 12,924	$ 12,138	$ 60,181	$ 10,938
Net gain (loss)			47,774	0
Unrealized loss on secured borrowings, fair value adjustment	$ 2,288	1,276	$ 3,239	5,999
Investments held | investment	2		2
Investments valued under the measurement alternative	$ 155,902		$ 155,902		$ 109,821
Proceeds from sale of investment valued under the measurement alternative			12,623	0
Gain on sale of investment			11,936	6,229
Equity Securities Sold December 2021
Schedule of Equity Method Investments [Line Items]
Investments valued under the measurement alternative	687		687
Proceeds from sale of investment valued under the measurement alternative	12,623
Gain on sale of investment	11,936
Individual Investors And Wealth Management Platform
Schedule of Equity Method Investments [Line Items]
Investments valued under the measurement alternative	13,500		13,500
ESG Reporting Metrics, Private Market Firms And Private Companies
Schedule of Equity Method Investments [Line Items]
Investments valued under the measurement alternative	$ 4,500		$ 4,500
Equity method investments in Partnerships
Schedule of Equity Method Investments [Line Items]
Percent interest in partnerships	1.00%		1.00%
Investment, Held As Collateral
Schedule of Equity Method Investments [Line Items]
Net gain (loss)	$ 2,288	$ 1,276	$ 3,239	$ 5,999
Investment, Measurement Alternative
Schedule of Equity Method Investments [Line Items]
Net gain (loss)	$ 19,768		$ 44,484