Fair Value Disclosures - Quantitative Information (Details) $ in Thousands	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	$ 6,974,002
Recurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee Asset	4,692		$ 6,237
Recurring | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	6,974,002		6,328,559
Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,999,788	$ 6,477,184	6,358,451	$ 6,163,052	$ 6,901,703	$ 6,973,567
Guarantee Asset	4,692		6,237
Recurring | Level 3 | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	6,974,002		6,328,559
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	19,243	19,061	19,254	19,500	19,248	19,171
Farmer Mac Guaranteed Securities | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	8,200		12,400
Farmer Mac Guaranteed Securities | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,974,002	6,450,212	6,328,559	6,138,759	6,877,405	6,947,701
USDA Securities: | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	1,851	2,275	4,401	4,793	5,050	6,695
AgVantage Securities | Recurring | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	6,965,761		6,316,145
AgVantage Securities | Recurring | Level 3 | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	6,965,761		6,316,145
AgVantage Securities | Farmer Mac Guaranteed Securities | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	6,965,761	6,440,396	6,316,145	$ 6,138,759	$ 6,877,405	$ 6,947,701
Farmer Mac Guaranteed USDA Securities | Recurring | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	8,241		12,414
Farmer Mac Guaranteed USDA Securities | Recurring | Level 3 | Farmer Mac Guaranteed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale, at fair value	8,241		12,414
Farmer Mac Guaranteed USDA Securities | Farmer Mac Guaranteed Securities | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 8,241	$ 9,816	$ 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	0.979		0.980
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	0.979		0.980
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	0.979		0.980
Discount rate | Minimum | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.054		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	0.046		0.009
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	0.049		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	0.056		0.014
Discount rate | Maximum | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.059		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	0.051		0.021
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	0.054		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	0.064		0.031
Discount rate | Weighted Average | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.057		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	0.049		0.017
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	0.051		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	0.058		0.028
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		0.08
CPR | Minimum | Discounted cash flow | Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Guarantee asset, measurement input	0.08		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	0.19		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	0.24		0.42
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	0.23		0.39