Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Maturities (Details) (Farmer Mac Guaranteed Securities and USDA Securities [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Due within one year, Amortized Cost	$ 785,824
Available-for-sale Securities, Due after one year through five years, Amortized Cost	1,561,316
Available-for-sale Securities, Due after five years through ten years, Amortized Cost	879,210
Available-for-sale Securities, Due after ten years, Amortized Cost	1,867,534
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Due within one year, Fair Value	788,681
Available-for-sale Securities, Due after one year through five years, Fair Value	1,578,618
Available-for-sale Securities, Due after five years through ten years, Fair Value	874,896
Available-for-sale Securities, Due after ten years, Fair Value	1,847,727
Available-for-sale Securities, Debt Maturities, Weighted-Average Yield, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Due within one year, Weighted-Average Yield	1.93%
Available-for-sale Securities, Due after one year through five years, Weighted-Average Yield	1.89%
Available-for-sale Securities, Due after five years through ten years, Weighted-Average Yield	1.79%
Available-for-sale Securities, Due after ten years, Weighted-Average Yield	2.59%
Available-for-sale Securities, Total Weighted-Average Yield	2.13%
Payment Guarantee [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Amortized Cost Basis	5,093,884	6,682,569
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale, at fair value	$ 5,089,922	$ 6,645,269

Available-for-sale Securities, Debt Maturities, after Ten Years, Weighted-Average Yield

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Available-for-sale Securities, Debt Maturities, Next Twelve Months, Weighted-Average Yield

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Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Weighted-Average Yield

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Available-for-sale Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing after the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing after the tenth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the next fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing in the next fiscal year following the latest fiscal year.

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