Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Schedule of Held-to-maturity Securities (Details) (USD $) In Thousands, unless otherwise specified	Jan. 01, 2014	Dec. 31, 2014
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Fair Value	$ 1,600,000
Farmer Mac Guaranteed Securities [Member]
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount		606,442
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount		1,178,000
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount		10,178
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment		1,794,620
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value		606,627
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value		1,183,351
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value		10,598
Held-to-maturity Securities, Fair Value		$ 1,800,576
Held-to-Maturity Securities, Debt Maturities, Weighted Average Yield, Single Maturity Date [Abstract]
Held-to-Maturity Securities, Debt Maturities, Next Twelve Months, Weighted-Average Yield		2.74%
Held-to-Maturity Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield		2.23%
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Weighted Average Yield		3.25%
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield		2.40%