Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Schedule of Held-to-maturity Securities (Details) $ in Thousands	Dec. 31, 2016 USD ($)
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	$ 3,158,456
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Fair Value	$ 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	2.90%
Held-to-Maturity Securities, Debt Maturities, After Ten Years, Weighted-Average Yield	3.25%
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	$ 281,312
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	902,648
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	170,400
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	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	281,722
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	903,580
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	163,138
Held-to-maturity Securities, Fair Value	$ 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	2.25%
Held-to-Maturity Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield	2.07%
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield	2.79%
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	$ 1,804,096
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	$ 1,718,204