Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Farmer Mac Guaranteed Securities and USDA Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	$ 6,045,828	$ 5,370,717
Available-for-sale Securities, Amortized Cost Basis	6,047,385	5,373,437
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	64,131	48,529
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	70,567	31,463
Available-for-sale, at fair value	6,040,949	5,390,503
Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,274,016
Held-to-maturity Securities, Fair Value	1,281,817
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	4,196,506	3,652,904
Available-for-sale Securities, Amortized Cost Basis	4,196,173	3,652,462
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	26,971	36,679
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	70,539	29,860
Available-for-sale, at fair value	4,152,605	3,659,281
USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-sale, at fair value	1,888,344	1,731,222
Trading Securities [Abstract]
Trading, at fair value	28,975	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)	1,557	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)	(333)	(442)
Institutional Credit [Member]
Schedule of Held-to-Maturity, Available-for-sale, and Trading Securities [Line Items]
Unamortized Premium/(Discount)	1,400
Institutional Credit [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	1,274,431	1,785,340
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,274,016	1,794,620
Held to Maturity; Unrealized Holding Gains	7,801	6,211
Held to Maturity - Unrealized Holding Loss	0	(255)
Held-to-maturity Securities, Fair Value	1,281,817	1,800,576
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	4,164,952	3,625,073
Available-for-sale Securities, Amortized Cost Basis	4,164,952	3,625,073
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	26,831	36,442
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	70,539	29,853
Available-for-sale, at fair value	4,121,244	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)	(415)	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)	(200)	200
USDA Guarantees [Member] \| Farmer Mac Guaranteed Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	31,554	27,831
Available-for-sale Securities, Amortized Cost Basis	31,221	27,389
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	140	237
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	7
Available-for-sale, at fair value	31,361	27,619
USDA Guarantees [Member] \| USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	1,849,322	1,717,813
Available-for-sale Securities, Amortized Cost Basis	1,851,212	1,720,975
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	37,160	11,850
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	28	1,603
Available-for-sale, at fair value	1,888,344	1,731,222
Trading Securities [Abstract]
Trading Securities Unpaid Principal Balance	27,129	38,412
Trading Securities, Debt, Amortized Cost	29,063	41,160
Trading Securities, Unrealized Gains	125	114
Trading Securities, Unrealized Holding Loss	213	964
Trading, at fair value	28,975	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)	(333)	(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)	1,890	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)	$ 1,934	$ 2,748

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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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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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