Fair Value Measurements - Information about Fair Value Measurements using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Discounted Cash Flow | Securitized Beneficial Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value of unobservable inputs	$ 27,021	$ 40,332
Discounted Cash Flow | Guarantees of Farmers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value of unobservable inputs	$ 255	$ 212
Discounted Cash Flow | Minimum | Securitized Beneficial Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Securitized market rate (as a percent)	3.44%	5.00%
Payment speed period	77 days	67 days
Discounted Cash Flow | Minimum | Guarantees of Farmers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Market interest rate (as a percent)	15.00%	15.00%
Discounted Cash Flow | Maximum | Securitized Beneficial Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Securitized market rate (as a percent)	3.45%	6.50%
Payment speed period	100 days	80 days
Discounted Cash Flow | Maximum | Guarantees of Farmers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Market interest rate (as a percent)	75.80%	70.00%
Historical Loss | Guarantees of Farmers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value of unobservable inputs	$ 2,536	$ 3,502
Historical Loss | Minimum | Guarantees of Farmers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Historical loss rate (as a percent)	2.20%	2.40%
Historical Loss | Maximum | Guarantees of Farmers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Historical loss rate (as a percent)	10.00%	10.00%