Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Schedule of Held-to-maturity Securities (Details) (Farmer Mac Guaranteed Securities [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
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	$ 558,291
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	1,094,340
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,652,631
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	558,749
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	1,097,514
Held-to-maturity Securities, Fair Value	$ 1,656,263
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	2.95%
Held-to-Maturity Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield	2.21%
Held-to-Maturity Securities, Debt Maturities, Weighted-Average Yield	2.44%