Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Schedule of Held-to-maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 3,100,508	$ 3,158,456
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Fair Value	$ 3,037,762	3,066,644
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	2.97%
Held-to-Maturity Securities, Debt Maturities, After Ten Years, Weighted-Average Yield	3.29%
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	$ 275,696
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	829,335
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	179,240
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,074,686	1,149,231
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	276,572
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	829,694
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	174,029
Held-to-maturity Securities, Fair Value	$ 1,078,149	$ 1,153,009
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	2.21%
Held-to-Maturity Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield	2.16%
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield	2.86%
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	$ 1,816,237
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	$ 1,757,467