Farmer Mac Guaranteed Securities and USDA Securities - Farmer Mac Guaranteed Securities and USDA Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Farmer Mac Guaranteed Securities and USDA Securities [Member]
Held-to-maturity:
Unpaid Principal Balance	$ 3,659,496	$ 4,207,531
Amortized Cost	3,707,553	4,262,792
Unrealized Gains	20,838	2,735
Unrealized Losses	(3,517)	(74,175)
Fair Value	3,724,874	4,191,352
Farmer Mac Guaranteed Securities [Member]
Held-to-maturity:
Unpaid Principal Balance	1,579,212	2,096,568
Amortized Cost	1,579,175	2,096,618
Unrealized Gains	14,627	2,735
Unrealized Losses	(1,593)	(11,948)
Fair Value	1,592,209	2,087,405
Available-for-sale:
Amortized Cost	6,923,315
Fair Value	7,035,668
USDA Securities [Member]
Trading:
Fair Value	9,201	9,999
Held-to-maturity Securities [Member] \| Farmer Mac Guaranteed Securities and USDA Securities [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	48,057	55,261
Available-for-sale:
Unamortized Premium/(Discount)	48,057	55,261
Trading:
Unamortized Premium/(Discount)	48,057	55,261
Held-to-maturity Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	(37)	50
Available-for-sale:
Unamortized Premium/(Discount)	(37)	50
Trading:
Unamortized Premium/(Discount)	(37)	50
Institutional Credit [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-maturity:
Unpaid Principal Balance	1,545,629	2,069,185
Amortized Cost	1,545,397	2,068,991
Unrealized Gains	14,003	2,637
Unrealized Losses	(1,593)	(11,948)
Fair Value	1,557,807	2,059,680
Available-for-sale:
Unpaid Principal Balance	6,923,464	6,003,733
Amortized Cost	6,923,315	6,003,529
Unrealized Gains	143,685	22,335
Unrealized Losses	(31,332)	(51,367)
Fair Value	7,035,668	5,974,497
Institutional Credit [Member] \| Held-to-maturity Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	(232)	(194)
Available-for-sale:
Unamortized Premium/(Discount)	(232)	(194)
Trading:
Unamortized Premium/(Discount)	(232)	(194)
Institutional Credit [Member] \| Available-for-sale Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	(149)	(204)
Available-for-sale:
Unamortized Premium/(Discount)	(149)	(204)
Trading:
Unamortized Premium/(Discount)	(149)	(204)
USDA Guarantees [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	(200)	(200)
Available-for-sale:
Unamortized Premium/(Discount)	(200)	(200)
Trading:
Unamortized Premium/(Discount)	(200)	(200)
USDA Guarantees [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-maturity:
Unpaid Principal Balance	33,583	27,383
Amortized Cost	33,778	27,627
Unrealized Gains	624	98
Unrealized Losses	0	0
Fair Value	34,402	27,725
USDA Guarantees [Member] \| USDA Securities [Member]
Held-to-maturity:
Unpaid Principal Balance	2,080,284	2,110,963
Amortized Cost	2,128,378	2,166,174
Unrealized Gains	6,211	0
Unrealized Losses	(1,924)	(62,227)
Fair Value	2,132,665	2,103,947
Trading:
Unpaid Principal Balance	8,818	9,591
Amortized Cost	9,388	10,292
Unrealized Gains	15	20
Unrealized Losses	(202)	(313)
Fair Value	$ 9,201	$ 9,999
Trading securities, weighted-average yield	5.23%	5.21%
USDA Guarantees [Member] \| Held-to-maturity Securities [Member] \| Farmer Mac Guaranteed Securities [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	$ 195	$ 244
Available-for-sale:
Unamortized Premium/(Discount)	195	244
Trading:
Unamortized Premium/(Discount)	195	244
USDA Guarantees [Member] \| Held-to-maturity Securities [Member] \| USDA Securities [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	48,094	55,211
Available-for-sale:
Unamortized Premium/(Discount)	48,094	55,211
Trading:
Unamortized Premium/(Discount)	48,094	55,211
USDA Guarantees [Member] \| Trading Securities [Member] \| USDA Securities [Member]
Held-to-maturity:
Unamortized Premium/(Discount)	570	701
Available-for-sale:
Unamortized Premium/(Discount)	570	701
Trading:
Unamortized Premium/(Discount)	$ 570	$ 701

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