Accounting Policies - Supplemental Cash Flows (Details) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jan. 02, 2013
Supplemental Cash and Non-cash Transactions [Line Items]
Interest	$ 54,674,000	$ 55,131,000
Income taxes	13,000,000	13,500,000
Loans acquired and securitized as Farmer Mac Guaranteed Securities	35,891,000	12,301,000
Real Estate, Acquisitions Through Foreclosures	1,034,000	0
Consolidation of guaranteed securities from off-balance sheet to Loans Held for Investment and Debt Securities of consolidated trusts held by third parties	35,891,000	12,301,000
Deconsolidation of guaranteed securities from Loans Held for Investment in consolidated trusts and debt securities of consolidated trusts held by third parties to off-balance sheet	0	460,261,000
Transfer of Loans Held-for-sale to Portfolio Loans	673,991,000	0
Transfer of Loans Held-for-sale to Loans Held-for Investment, unamortized discount			$ (5,900,000)
Maximum [Member]
Supplemental Cash and Non-cash Transactions [Line Items]
Cash Equivalent Maturity Period	3 months