Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Schedule of Available-for-sale Securities (Details) (Farmer Mac Guaranteed Securities and USDA Securities [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Due within one year, Amortized Cost	$ 108,230
Available-for-sale Securities, Due after one year through five years, Amortized Cost	1,606,307
Available-for-sale Securities, Due after five years through ten years, Amortized Cost	1,291,284
Available-for-sale Securities, Due after ten years, Amortized Cost	2,025,795
Available-for-sale Securities, Amortized Cost Basis	5,031,616	6,682,569
Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract]
Available-for-sale Securities, Due within one year, Fair Value	103,969
Available-for-sale Securities, Due after one year through five years, Fair Value	1,631,275
Available-for-sale Securities, Due after five years through ten years, Fair Value	1,294,016
Available-for-sale Securities, Due after ten years, Fair Value	2,015,396
Available-for-sale, at fair value	$ 5,044,656	$ 6,645,269
Available-for-sale Securities, Debt Maturities, Weighted Average Yield, Single Maturity Date [Abstract]
Available-for-sale Securities, Due within one year, Weighted-Average Yield	0.91%
Available-for-sale Securities, Due after one year through five years, Weighted-Average Yield	1.87%
Available-for-sale Securities, Due after five years through ten years, Weighted-Average Yield	1.89%
Available-for-sale Securities, Due after ten years, Weighted-Average Yield	2.61%
Available-for-sale Securities, Total Weighted-Average Yield	2.15%