Fair Value Measurements Information About Fair Value Measurements Using Significant Unobservable Inputs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2012
Securitized Beneficial Interests [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value of unobservable inputs	35,368
Guarantees of Farmers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value of unobservable inputs	1,958
Guarantees of Unconsolidated Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value of unobservable inputs	3,845
Historical Loss Valuation Technique [Member] | Minimum [Member] | Guarantees of Farmers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Historical Loss	6.00%
Historical Loss Valuation Technique [Member] | Maximum [Member] | Guarantees of Farmers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Historical Loss	8.00%
Discounted Cash Flow Valuation Technique [Member] | Guarantees of Unconsolidated Subsidiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Market Interest Rate	12.00%
Discounted Cash Flow Valuation Technique [Member] | Minimum [Member] | Securitized Beneficial Interests [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Securitized Market Rate	2.58%
Payment Speed	42 days
Discounted Cash Flow Valuation Technique [Member] | Maximum [Member] | Securitized Beneficial Interests [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Securitized Market Rate	3.91%
Payment Speed	64 days