Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Schedule of Held-to-maturity Securities (Details) $ in Thousands	Mar. 31, 2016 USD ($)
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Held-to-Maturity Securities, Debt Maturities, Weighted Average Yield, Single Maturity Date [Abstract]
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Weighted Average Yield	3.43%
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	$ 703,005
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	494,656
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	9,688
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,207,349
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	704,257
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	505,844
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	10,409
Held-to-maturity Securities, Fair Value	$ 1,220,510
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	2.32%
Held-to-Maturity Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield	2.35%
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield	2.34%