Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Farmer Mac Guaranteed Securities and USDA Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	$ 5,841,735	$ 5,370,717
Available-for-sale Securities, Amortized Cost Basis	5,843,932	5,373,437
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	75,578	48,529
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	42,896	31,463
Available-for-sale, at fair value	5,876,614	5,390,503
Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,822,027
Held-to-maturity Securities, Fair Value	1,836,296
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	4,056,073	3,652,904
Available-for-sale Securities, Amortized Cost Basis	4,055,734	3,652,462
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	38,335	36,679
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	42,861	29,860
Available-for-sale, at fair value	4,051,208	3,659,281
USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-sale, at fair value	1,825,406	1,731,222
Trading Securities [Abstract]
Trading, at fair value	33,770	40,310
Available-for-sale Securities [Member] \| Farmer Mac Guaranteed Securities and USDA Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	2,197	2,720
Available-for-sale Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	(339)	(442)
Institutional Credit [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	2,100	2,400
Institutional Credit [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	1,819,159	1,785,340
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,822,027	1,794,620
Held to Maturity; Unrealized Holding Gains	14,269	6,211
Held to Maturity - Unrealized Holding Loss	0	(255)
Held-to-maturity Securities, Fair Value	1,836,296	1,800,576
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	4,022,251	3,625,073
Available-for-sale Securities, Amortized Cost Basis	4,022,251	3,625,073
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	36,810	36,442
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	42,861	29,853
Available-for-sale, at fair value	4,016,200	3,631,662
Institutional Credit [Member] \| Held-to-maturity Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	2,868	9,280
Institutional Credit [Member] \| Available-for-sale Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	0	0
USDA Guarantees [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	1,200	(200)
USDA Guarantees [Member] \| Farmer Mac Guaranteed Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	33,822	27,831
Available-for-sale Securities, Amortized Cost Basis	33,483	27,389
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,525	237
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	7
Available-for-sale, at fair value	35,008	27,619
USDA Guarantees [Member] \| USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	1,785,662	1,717,813
Available-for-sale Securities, Amortized Cost Basis	1,788,198	1,720,975
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	37,243	11,850
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	35	1,603
Available-for-sale, at fair value	1,825,406	1,731,222
Trading Securities [Abstract]
Trading Securities Unpaid Principal Balance	32,058	38,412
Trading Securities, Debt, Amortized Cost	34,442	41,160
Trading Securities, Unrealized Gains	100	114
Trading Securities, Unrealized Holding Loss	772	964
Trading, at fair value	33,770	40,310
USDA Guarantees [Member] \| Available-for-sale Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	(339)	(442)
USDA Guarantees [Member] \| Available-for-sale Securities [Member] \| USDA Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	2,536	3,162
USDA Guarantees [Member] \| Trading Securities [Member] \| USDA Securities [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	$ 2,384	$ 2,748

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[Line Items] for Schedule of held to maturity, available for sale, and trading securities which includes, but is not limited to changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis and other related disclosures

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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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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The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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