Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Schedule of Held-to-maturity Securities (Details) - Jun. 30, 2015 - USD ($) $ in Thousands	Total
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Held-to-Maturity Securities, Debt Maturities, Weighted Average Yield, Single Maturity Date [Abstract]
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Weighted-Average Yield	3.35%
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	$ 679,891
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	1,135,536
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,822,027
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	680,697
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	1,148,735
Held-to-maturity Securities, Fair Value	$ 1,836,296
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	2.66%
Held-to-Maturity Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield	2.35%
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield	2.46%
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	$ 6,600
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	$ 6,864