Fair Value Measurements - Schedule of Fair Value of Liabilities and Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Mar. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	$ 233,398	$ 131,858
Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	27,471	17,028
Partnership And LLC Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	205,927	114,830
Level III
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	27,500	13,700
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration obligation	67,115	53,449
Total liabilities	67,115	53,449
Total assets	27,471	13,694
Fair Value, Recurring | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	27,471	12,421
Fair Value, Recurring | Partnership And LLC Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests		1,273
Fair Value, Recurring | Level I
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration obligation	0	0
Total liabilities	0	0
Total assets	0	0
Fair Value, Recurring | Level I | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	0	0
Fair Value, Recurring | Level I | Partnership And LLC Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests		0
Fair Value, Recurring | Level II
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration obligation	0	0
Total liabilities	0	0
Total assets	0	0
Fair Value, Recurring | Level II | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	0	0
Fair Value, Recurring | Level II | Partnership And LLC Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests		0
Fair Value, Recurring | Level III
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration obligation	67,115	53,449
Total liabilities	67,115	53,449
Total assets	27,471	13,694
Fair Value, Recurring | Level III | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests	$ 27,471	12,421
Fair Value, Recurring | Level III | Partnership And LLC Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Partnership and LLC interests		$ 1,273