Fair Value Disclosures - Unobservable Input Reconciliation (Details) - Level 3 - Recurring - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 6,973,567	$ 7,170,850	$ 6,003,211
Purchases	1,161,912	974,237	2,091,566
Sales	0	0	(57,853)
Settlements	(1,617,039)	(1,400,130)	(1,021,706)
Allowance for Losses	31	(345)
Realized and unrealized losses included in Income	(176,180)	202,757	181,470
Unrealized gains included in Other Comprehensive Income	16,160	26,198	(25,838)
Ending Balance	6,358,451	6,973,567	7,170,850
Floating rate auction-rate certificates backed by Government guaranteed student loans \| Floating Interest Rate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	19,171
Ending Balance	19,254	19,171
Floating rate auction-rate certificates backed by Government guaranteed student loans \| Floating Interest Rate \| Available-for-Sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	19,171	18,912	18,715
Purchases	0	0	0
Sales	0	0	0
Settlements	0	0	0
Allowance for Losses	(16)	(36)
Realized and unrealized losses included in Income	0	0	0
Unrealized gains included in Other Comprehensive Income	99	295	197
Ending Balance	19,254	19,171	18,912
Available-for-sale securities \| Available-for-Sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	19,171	18,912	18,715
Purchases	0	0	0
Sales	0	0	0
Settlements	0	0	0
Allowance for Losses	(16)	(36)
Realized and unrealized losses included in Income	0	0	0
Unrealized gains included in Other Comprehensive Income	99	295	197
Ending Balance	19,254	19,171	18,912
Farmer Mac Guaranteed Securities \| AgVantage Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,947,701
Ending Balance	6,316,145	6,947,701
Farmer Mac Guaranteed Securities \| Available-for-Sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,947,701	7,143,025	5,974,497
Purchases	1,155,675	974,237	2,033,713
Sales	0	0	0
Settlements	(1,614,861)	(1,397,861)	(1,020,294)
Allowance for Losses	47	(309)
Realized and unrealized losses included in Income	(176,064)	202,706	181,144
Unrealized gains included in Other Comprehensive Income	16,061	25,903	(26,035)
Ending Balance	6,328,559	6,947,701	7,143,025
Farmer Mac Guaranteed Securities \| Available-for-Sale Securities \| AgVantage Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,947,701	7,143,025	5,974,497
Purchases	1,143,115	974,237	2,033,713
Sales	0	0	0
Settlements	(1,614,598)	(1,397,861)	(1,020,294)
Allowance for Losses	47	(309)
Realized and unrealized losses included in Income	(176,064)	202,706	181,144
Unrealized gains included in Other Comprehensive Income	15,944	25,903	(26,035)
Ending Balance	6,316,145	6,947,701	7,143,025
Farmer Mac Guaranteed Securities \| Available-for-Sale Securities \| Farmer Mac Guaranteed USDA Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	0
Purchases	12,560
Sales	0
Settlements	(263)
Allowance for Losses	0
Realized and unrealized losses included in Income	0
Unrealized gains included in Other Comprehensive Income	117
Ending Balance	12,414	0
USDA Securities:
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,695	8,913	9,999
Purchases	0	0	57,853
Sales	0	0	(57,853)
Settlements	(2,178)	(2,269)	(1,412)
Allowance for Losses
Realized and unrealized losses included in Income	(116)	51	326
Unrealized gains included in Other Comprehensive Income	0	0	0
Ending Balance	4,401	6,695	8,913
USDA Securities: \| Available-for-Sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		0	0
Purchases			57,853
Sales			(57,853)
Settlements			0
Realized and unrealized losses included in Income			0
Unrealized gains included in Other Comprehensive Income			0
Ending Balance			0
USDA Securities: \| Debt Securities, Trading
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,695	8,913	9,999
Purchases	0	0	0
Sales	0	0	0
Settlements	(2,178)	(2,269)	(1,412)
Allowance for Losses	0	0
Realized and unrealized losses included in Income	(116)	51	326
Unrealized gains included in Other Comprehensive Income	0	0	0
Ending Balance	4,401	6,695	$ 8,913
Guarantee and commitment obligations:
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	0
Purchases	6,237
Sales	0
Settlements	0
Allowance for Losses	0
Realized and unrealized losses included in Income	0
Unrealized gains included in Other Comprehensive Income	0
Ending Balance	6,237	0
Guarantee and commitment obligations: \| Guarantee Asset
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	0
Purchases	6,237
Sales	0
Settlements	0
Allowance for Losses	0
Realized and unrealized losses included in Income	0
Unrealized gains included in Other Comprehensive Income	0
Ending Balance	$ 6,237	$ 0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Allowance for Credit Loss

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
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-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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