Investments - Reconciliation of Other Investments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Reconciliation Of Other Investments [Roll Forward]
Other investments, beginning balance	$ 16,613	$ 12,488
Purchases	0	3,967
Sales / Maturities	(973)	(973)
Net (loss) gain	273	431
Other investments, ending balance	15,913	15,913
Private equity funds
Reconciliation Of Other Investments [Roll Forward]
Other investments, beginning balance	5,911
Purchases	0	2,092
Sales / Maturities	0	0
Net (loss) gain	(75)	10
Other investments, ending balance	5,836	5,836
Direct credit co-investments
Reconciliation Of Other Investments [Roll Forward]
Other investments, beginning balance	4,013	3,940
Purchases	0	0
Sales / Maturities	(973)	(973)
Net (loss) gain	53	126
Other investments, ending balance	3,093	3,093
Direct equity co-investments
Reconciliation Of Other Investments [Roll Forward]
Other investments, beginning balance	6,689	4,814
Purchases	0	1,875
Sales / Maturities	0	0
Net (loss) gain	295	295
Other investments, ending balance	$ 6,984	$ 6,984