Farmer Mac Guaranteed Securities and USDA Securities - Schedule of On-Balance Sheet Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Farmer Mac Guaranteed Securities
Held-to-maturity:
Unpaid Principal Balance	$ 1,040,918	$ 1,175,886
Amortized Cost	1,040,939	1,175,912
Allowance for losses	(182)	(120)
Unrealized Gains	17,607	25,259
Unrealized Losses	(4,374)	(61)
Fair Value	1,053,990	1,200,990
Available-for-sale:
Amortized cost	6,618,871
USDA Securities:
Trading:
Fair Value	5,050	6,695
Farmer Mac Guaranteed Securities and USDA Securities
Held-to-maturity:
Unpaid Principal Balance	3,463,515	3,622,436
Amortized Cost	3,486,657	3,649,538
Allowance for losses	(182)	(120)
Unrealized Gains	40,025	183,007
Unrealized Losses	(5,517)	(621)
Fair Value	3,520,983	3,831,804
Held-to-Maturity Securities \| Farmer Mac Guaranteed Securities
Held-to-maturity:
Unamortized Premium/(Discount)	21	26
Available-for-sale:
Unamortized Premium/(Discount)	21	26
Trading:
Unamortized Premium/(Discount)	21	26
Held-to-Maturity Securities \| Farmer Mac Guaranteed Securities and USDA Securities
Held-to-maturity:
Unamortized Premium/(Discount)	23,142	27,102
Available-for-sale:
Unamortized Premium/(Discount)	23,142	27,102
Trading:
Unamortized Premium/(Discount)	23,142	27,102
USDA Guarantees
Held-to-maturity:
Unamortized Premium/(Discount)	(41,000)	100
Available-for-sale:
Unamortized Premium/(Discount)	(41,000)	100
Trading:
Unamortized Premium/(Discount)	(41,000)	100
USDA Guarantees \| Farmer Mac Guaranteed Securities
Held-to-maturity:
Unpaid Principal Balance	28,756	34,456
Amortized Cost	28,797	34,537
Allowance for losses	0	0
Unrealized Gains	561	1,273
Unrealized Losses	(178)	0
Fair Value	29,180	35,810
USDA Guarantees \| USDA Securities:
Held-to-maturity:
Unpaid Principal Balance	2,422,597	2,446,550
Amortized Cost	2,445,718	2,473,626
Allowance for losses	0	0
Unrealized Gains	22,418	157,748
Unrealized Losses	(1,143)	(560)
Fair Value	2,466,993	2,630,814
Trading:
Unpaid Principal Balance	4,904	6,413
Amortized Cost	5,042	6,611
Allowance for losses	0	0
Unrealized Gains	22	84
Unrealized Losses	(14)	0
Fair Value	$ 5,050	$ 6,695
Trading securities, weighted-average yield	5.06%	5.05%
USDA Guarantees \| Held-to-Maturity Securities \| Farmer Mac Guaranteed Securities
Held-to-maturity:
Unamortized Premium/(Discount)	$ 41	$ 81
Available-for-sale:
Unamortized Premium/(Discount)	41	81
Trading:
Unamortized Premium/(Discount)	41	81
USDA Guarantees \| Held-to-Maturity Securities \| USDA Securities:
Held-to-maturity:
Unamortized Premium/(Discount)	23,121	27,076
Available-for-sale:
Unamortized Premium/(Discount)	23,121	27,076
Trading:
Unamortized Premium/(Discount)	23,121	27,076
USDA Guarantees \| Trading \| USDA Securities:
Held-to-maturity:
Unamortized Premium/(Discount)	138	198
Available-for-sale:
Unamortized Premium/(Discount)	138	198
Trading:
Unamortized Premium/(Discount)	138	198
AgVantage Securities
Trading:
Available-for-sale, accrued interest excluded	32,000	32,300
Held-to-maturity, accrued interest excluded	31,200	44,700
Trading securities, accrued interest excluded	100	200
AgVantage Securities \| Farmer Mac Guaranteed Securities
Held-to-maturity:
Unpaid Principal Balance	1,012,162	1,141,430
Amortized Cost	1,012,142	1,141,375
Allowance for losses	(182)	(120)
Unrealized Gains	17,046	23,986
Unrealized Losses	(4,196)	(61)
Fair Value	1,024,810	1,165,180
Available-for-sale:
Unpaid Principal Balance	6,617,498	6,593,518
Amortized cost	6,618,871	6,594,992
Allowance for losses	(220)	(310)
Unrealized Gains	271,223	368,257
Unrealized Losses	(12,469)	(15,238)
Fair Value	6,877,405
AgVantage Securities \| Held-to-Maturity Securities \| Farmer Mac Guaranteed Securities
Held-to-maturity:
Unamortized Premium/(Discount)	(20)	(55)
Available-for-sale:
Unamortized Premium/(Discount)	(20)	(55)
Trading:
Unamortized Premium/(Discount)	(20)	(55)
AgVantage Securities \| Available-for-Sale Securities \| Farmer Mac Guaranteed Securities
Held-to-maturity:
Unamortized Premium/(Discount)	1,373	1,474
Available-for-sale:
Unamortized Premium/(Discount)	1,373	1,474
Trading:
Unamortized Premium/(Discount)	$ 1,373	$ 1,474

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