Fair Value Disclosures - Quantitative Information (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 6,328,559
Recurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee Asset	6,237
Recurring | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,328,559	$ 6,947,701
Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,358,451	6,973,567	$ 7,170,850	$ 6,003,211
Guarantee Asset	6,237
Recurring | Level 3 | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,328,559	6,947,701
Floating rate auction-rate certificates backed by Government guaranteed student loans | Recurring | Level 3 | Floating Interest Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	19,254	19,171
Farmer Mac Guaranteed Securities | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	12,400
USDA Securities: | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	4,401	6,695	$ 8,913	$ 9,999
AgVantage Securities | Recurring | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,316,145	6,947,701
AgVantage Securities | Recurring | Level 3 | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,316,145	6,947,701
AgVantage Securities | Farmer Mac Guaranteed Securities | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,316,145	$ 6,947,701
Farmer Mac Guaranteed USDA Securities | Recurring | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	12,414
Farmer Mac Guaranteed USDA Securities | Recurring | Level 3 | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 12,414
Range of broker quotes | Minimum | Floating rate auction-rate certificates backed by Government guaranteed student loans | Indicative bids | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.980	0.975
Range of broker quotes | Maximum | Floating rate auction-rate certificates backed by Government guaranteed student loans | Indicative bids | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.980	0.975
Range of broker quotes | Weighted Average | Floating rate auction-rate certificates backed by Government guaranteed student loans | Indicative bids | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.980	0.975
Discount rate | Minimum | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.054
Discount rate | Minimum | AgVantage Securities | Farmer Mac Guaranteed Securities | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.009	0.008
Discount rate | Minimum | Farmer Mac Guaranteed USDA Securities | Farmer Mac Guaranteed Securities | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.023
Discount rate | Minimum | USDA Securities | USDA Securities: | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
USDA securities, measurement input	0.014	0.009
Discount rate | Maximum | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.058
Discount rate | Maximum | AgVantage Securities | Farmer Mac Guaranteed Securities | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.021	0.023
Discount rate | Maximum | Farmer Mac Guaranteed USDA Securities | Farmer Mac Guaranteed Securities | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.028
Discount rate | Maximum | USDA Securities | USDA Securities: | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
USDA securities, measurement input	0.031	0.019
Discount rate | Weighted Average | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.056
Discount rate | Weighted Average | AgVantage Securities | Farmer Mac Guaranteed Securities | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.017	0.013
Discount rate | Weighted Average | Farmer Mac Guaranteed USDA Securities | Farmer Mac Guaranteed Securities | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.026
Discount rate | Weighted Average | USDA Securities | USDA Securities: | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
USDA securities, measurement input	0.028	0.014
CPR | Farmer Mac Guaranteed USDA Securities | Farmer Mac Guaranteed Securities | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities, measurement input	0.08
CPR | Minimum | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.07
CPR | Minimum | USDA Securities | USDA Securities: | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
USDA securities, measurement input	0.25	0.25
CPR | Maximum | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.12
CPR | Maximum | USDA Securities | USDA Securities: | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
USDA securities, measurement input	0.42	0.49
CPR | Weighted Average | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.08
CPR | Weighted Average | USDA Securities | USDA Securities: | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
USDA securities, measurement input	0.39	0.44