Investments, at Fair Value - Investments at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments held by Customer ExAlt Trusts (related party of $552 and $76,154)	$ 293,916	$ 385,851
Debt securities available-for-sale	2,962	76,898
Equity securities without readily determinable fair value	26,800	21,600
Ben
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments held by Customer ExAlt Trusts (related party of $552 and $76,154)	0	0
Public equity securities and option	0	4,742
Debt securities available-for-sale	0	620
Equity securities without readily determinable fair value	6	0
Total investments, at fair value	6	5,362
Customer ExAlt Trusts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments held by Customer ExAlt Trusts (related party of $552 and $76,154)	293,916	385,851
Public equity securities and option	4,897	8,087
Debt securities available-for-sale	2,962	76,278
Equity securities without readily determinable fair value	27,338	21,643
Total investments, at fair value	$ 329,113	$ 491,859