Notes Payable (Details)	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Sep. 30, 2020	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Accordion feature permitting the maximum aggregate commitments to increase	$ 685,000,000.0			$ 685,000,000.0
Standby letters of credit	$ 300,000.0			$ 300,000.0
Extension period				1 year
Commitment fee percentage				0.50%
Unused borrowing capacity fee				$ 1,300,000	$ 1,000,000.0	$ 1,100,000
Effective interest rate	5.80%			5.80%	5.80%	6.70%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 685,000,000.0			$ 685,000,000.0
Amount outstanding	405,000,000.0			$ 405,000,000.0
Expiration date				Jun. 07, 2024
Unused amount available	181,400,000			$ 181,400,000
Minimum net worth	$ 325,000,000.0		$ 365,000,000.0
Fixed conversion ratio	2.75	2.25
Maximum ratio to total debt				2.0
Maximum collateral performance indicator percentage				24.00%
Expiration period				60 days
Minimum
Line of Credit Facility [Line Items]
Interest rate	3.50%			3.50%
Maximum
Line of Credit Facility [Line Items]
Interest rate	4.50%			4.50%