Variable Interest Entities - Consolidated VIEs (Details) - USD ($)	Sep. 30, 2019	Mar. 31, 2019
Variable Interest Entity [Line Items]
Deferred incentive fee revenue	$ 3,704,000	$ 3,704,000
Primary Beneficiary
Variable Interest Entity [Line Items]
Total assets of consolidated VIEs	11,485,000	11,648,000
Total liabilities of consolidated VIEs	0	0
Deferred incentive fee revenue	$ 3,704,000	$ 3,704,000