Organization (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Product Information [Line Items]
On and Off Balance Sheet Program Assets, At Principal Balance	$ 13,015,188,000	$ 11,913,302,000	$ 12,216,709,000
Farmer Mac I [Member]
Product Information [Line Items]
On and Off Balance Sheet Program Assets, At Principal Balance	9,056,489,000	8,057,027,000	8,188,628,000
Farmer Mac II [Member]
Product Information [Line Items]
On and Off Balance Sheet Program Assets, At Principal Balance	1,615,579,000	1,513,177,000	1,385,398,000
Rural Utilities [Member]
Product Information [Line Items]
On and Off Balance Sheet Program Assets, At Principal Balance	2,343,120,000	2,343,098,000	2,642,683,000
Discount Notes [Member]
Product Information [Line Items]
Notes Payable	5,000,000,000
Medium-term Notes
Product Information [Line Items]
Notes Payable	6,600,000,000
Off-balance sheet [Member] | Rural Utilities Farmer Mac Guaranteed Securities AgVantage [Member]
Product Information [Line Items]
On and Off Balance Sheet Program Assets, At Principal Balance	12,700,000
On-balance sheet [Member] | Rural Utilities [Member]
Product Information [Line Items]
On and Off Balance Sheet Program Assets, At Principal Balance	$ 2,300,000,000