Farmer Mac Guaranteed Securities and USDA Guaranteed Securities - Farmer Mac Guaranteed Securities and USDA Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	$ 6,459,339	$ 6,045,828
Available-for-sale Securities, Amortized Cost Basis	6,461,020	6,047,385
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	89,222	64,131
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	76,724	70,567
Available-for-sale, at fair value	6,473,518	6,040,949
Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,207,349
Held-to-maturity Securities, Fair Value	1,220,510
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	4,598,991	4,196,506
Available-for-sale Securities, Amortized Cost Basis	4,598,676	4,196,173
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	43,477	26,971
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	76,649	70,539
Available-for-sale, at fair value	4,565,504	4,152,605
USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-sale, at fair value	1,908,014	1,888,344
Trading Securities [Abstract]
Trading, at fair value	26,869	28,975
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)	1,681	1,557
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)	(315)	(333)
Institutional Credit [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-Maturity Securities [Abstract]
Held-to-Maturity Unpaid Principal Balance	1,208,802	1,274,431
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	1,207,349	1,274,016
Held to Maturity; Unrealized Holding Gains	13,164	7,801
Held to Maturity - Unrealized Holding Loss	(3)	0
Held-to-maturity Securities, Fair Value	1,220,510	1,281,817
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	4,567,953	4,164,952
Available-for-sale Securities, Amortized Cost Basis	4,567,953	4,164,952
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	43,444	26,831
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	76,587	70,539
Available-for-sale, at fair value	4,534,810	4,121,244
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)	(1,453)	(415)
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)	(300)	(200)
USDA Guarantees [Member] \| Farmer Mac Guaranteed Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	31,038	31,554
Available-for-sale Securities, Amortized Cost Basis	30,723	31,221
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	33	140
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	62	0
Available-for-sale, at fair value	30,694	31,361
USDA Guarantees [Member] \| USDA Securities [Member]
Available-for-sale Securities [Abstract]
Available-for-Sale Securities Unpaid Principal Balance	1,860,348	1,849,322
Available-for-sale Securities, Amortized Cost Basis	1,862,344	1,851,212
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	45,745	37,160
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	75	28
Available-for-sale, at fair value	1,908,014	1,888,344
Trading Securities [Abstract]
Trading Securities Unpaid Principal Balance	24,928	27,129
Trading Securities, Debt, Amortized Cost	26,697	29,063
Trading Securities, Unrealized Gains	302	125
Trading Securities, Unrealized Holding Loss	130	213
Trading, at fair value	26,869	28,975
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)	(315)	(333)
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)	1,996	1,890
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)	$ 1,769	$ 1,934

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

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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 of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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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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