Fair Value Measurements - Narrative (Details) $ in Thousands	3 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)
Guarantees of Farmers | Discounted Cash Flow Valuation Technique | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Market interest rate (as a percent)	15.00%
Securitized Beneficial Interests
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Unrealized losses for securitized beneficial interests	$ 468	$ 946
Securitized Beneficial Interests | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Payment speed	70 days
Discount rate (as a percent)	2.00%
Securitized Beneficial Interests | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Payment speed	72 days
Discount rate (as a percent)	3.60%
Loss Severity | Guarantees of Farmers | Historical Loss Valuation Technique | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Historical loss (as a percent)	0.022
Loss Severity | Guarantees of Farmers | Historical Loss Valuation Technique | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Historical loss (as a percent)	0.100
Treasury Notes Interest Rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Measurement input of debt instrument (as a percent)	0.003
Treasury Notes Interest Rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Measurement input of debt instrument (as a percent)	0.006
Borrowings Rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Measurement input of debt instrument (as a percent)	0.070
Borrowings Rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Measurement input of debt instrument (as a percent)	0.107