Business Segment Reporting - Core Earnings (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) segment	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment	7
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	$ 61,875	$ 53,251
Less: reconciling adjustments	0	0
Net effective spread	0	0
Guarantee and commitment fees	3,695	3,030
Other income/(expense)	16,686	4,863
Total revenues	82,256	61,144
(Provision for)/release of losses	(56)	(913)
Release of reserve for losses	110	944
Operating expenses	(21,388)	(18,881)
Total non-interest expense	(21,278)	(17,937)
Core earnings before income taxes	60,922	42,294
Income tax (expense)/benefit	(13,085)	(9,067)
Core earnings before preferred stock dividends	47,837	33,227
Preferred stock dividends	(6,791)	(5,269)
Loss on retirement of preferred stock		0
Segment core earnings	41,046	27,958
Total Assets	25,789,414	24,013,911	$ 25,145,491
Total on- and off-balance sheet program assets at principal balance	24,243,410	21,862,531
Reconciling Adjustments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0
Less: reconciling adjustments	4,036	(608)
Net effective spread	4,036	(608)
Guarantee and commitment fees	(862)	(1,210)
Other income/(expense)	16,172	4,412
Total revenues	19,346	2,594
(Provision for)/release of losses	0	0
Release of reserve for losses	0	0
Operating expenses	0	0
Total non-interest expense	0	0
Core earnings before income taxes	19,346	2,594
Income tax (expense)/benefit	(4,061)	(547)
Core earnings before preferred stock dividends	15,285	2,047
Preferred stock dividends	0	0
Loss on retirement of preferred stock		0
Segment core earnings	15,285	2,047
Total Assets	0	0
Total on- and off-balance sheet program assets at principal balance	0	0
Farm & Ranch | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	31,354	27,646
Less: reconciling adjustments	(1,000)	(1,184)
Net effective spread	30,354	26,462
Guarantee and commitment fees	4,216	3,908
Other income/(expense)	400	572
Total revenues	34,970	30,942
(Provision for)/release of losses	(510)	0
Release of reserve for losses	75	731
Operating expenses	0	0
Total non-interest expense	75	731
Core earnings before income taxes	34,535	31,673
Income tax (expense)/benefit	(7,252)	(6,650)
Core earnings before preferred stock dividends	27,283	25,023
Preferred stock dividends	0	0
Loss on retirement of preferred stock		0
Segment core earnings	27,283	25,023
Total Assets	13,610,138	12,289,354
Total on- and off-balance sheet program assets at principal balance	16,575,595	14,738,052
Corporate AgFinance | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	7,209	6,921
Less: reconciling adjustments	0	0
Net effective spread	7,209	6,921
Guarantee and commitment fees	19	8
Other income/(expense)	114	0
Total revenues	7,342	6,929
(Provision for)/release of losses	(515)	(61)
Release of reserve for losses	0	0
Operating expenses	0	0
Total non-interest expense	0	0
Core earnings before income taxes	6,827	6,868
Income tax (expense)/benefit	(1,434)	(1,441)
Core earnings before preferred stock dividends	5,393	5,427
Preferred stock dividends	0	0
Loss on retirement of preferred stock		0
Segment core earnings	5,393	5,427
Total Assets	1,491,127	1,644,837
Total on- and off-balance sheet program assets at principal balance	1,540,760	1,647,796
Rural  Utilities | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	3,193	1,754
Less: reconciling adjustments	(34)	(34)
Net effective spread	3,159	1,720
Guarantee and commitment fees	286	319
Other income/(expense)	0	1
Total revenues	3,445	2,040
(Provision for)/release of losses	1,169	(633)
Release of reserve for losses	35	213
Operating expenses	0	0
Total non-interest expense	35	213
Core earnings before income taxes	4,649	1,620
Income tax (expense)/benefit	(976)	(341)
Core earnings before preferred stock dividends	3,673	1,279
Preferred stock dividends	0	0
Loss on retirement of preferred stock		0
Segment core earnings	3,673	1,279
Total Assets	5,480,668	4,836,306
Total on- and off-balance sheet program assets at principal balance	6,006,446	5,382,835
Renewable Energy | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	375	248
Less: reconciling adjustments	0	0
Net effective spread	375	248
Guarantee and commitment fees	36	5
Other income/(expense)	0	0
Total revenues	411	253
(Provision for)/release of losses	(202)	(195)
Release of reserve for losses	0	0
Operating expenses	0	0
Total non-interest expense	0	0
Core earnings before income taxes	209	58
Income tax (expense)/benefit	(44)	(12)
Core earnings before preferred stock dividends	165	46
Preferred stock dividends	0	0
Loss on retirement of preferred stock		0
Segment core earnings	165	46
Total Assets	92,132	83,352
Total on- and off-balance sheet program assets at principal balance	120,609	93,848
Funding | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	19,740	16,568
Less: reconciling adjustments	(3,002)	1,826
Net effective spread	16,738	18,394
Guarantee and commitment fees	0	0
Other income/(expense)	0	0
Total revenues	16,738	18,394
(Provision for)/release of losses	0	0
Release of reserve for losses	0	0
Operating expenses	0	0
Total non-interest expense	0	0
Core earnings before income taxes	16,738	18,394
Income tax (expense)/benefit	(3,515)	(3,863)
Core earnings before preferred stock dividends	13,223	14,531
Preferred stock dividends	0	0
Loss on retirement of preferred stock		0
Segment core earnings	13,223	14,531
Total Assets	0	0
Total on- and off-balance sheet program assets at principal balance	0	0
Investments | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	4	114
Less: reconciling adjustments	0	0
Net effective spread	4	114
Guarantee and commitment fees	0	0
Other income/(expense)	0	0
Total revenues	4	114
(Provision for)/release of losses	2	(24)
Release of reserve for losses	0	0
Operating expenses	0	0
Total non-interest expense	0	0
Core earnings before income taxes	6	90
Income tax (expense)/benefit	(1)	(19)
Core earnings before preferred stock dividends	5	71
Preferred stock dividends	0	0
Loss on retirement of preferred stock		0
Segment core earnings	5	71
Total Assets	4,995,154	5,128,901
Total on- and off-balance sheet program assets at principal balance	0	0
Corporate | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0
Less: reconciling adjustments	0	0
Net effective spread	0	0
Guarantee and commitment fees	0	0
Other income/(expense)	0	(122)
Total revenues	0	(122)
(Provision for)/release of losses	0	0
Release of reserve for losses	0	0
Operating expenses	(21,388)	(18,881)
Total non-interest expense	(21,388)	(18,881)
Core earnings before income taxes	(21,388)	(19,003)
Income tax (expense)/benefit	4,198	3,806
Core earnings before preferred stock dividends	(17,190)	(15,197)
Preferred stock dividends	(6,791)	(5,269)
Loss on retirement of preferred stock		0
Segment core earnings	(23,981)	(20,466)
Total Assets	120,195	31,161
Total on- and off-balance sheet program assets at principal balance	$ 0	$ 0