Business Segment Reporting - Core Earnings (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			7
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	$ 78,677	$ 63,914	$ 157,735	$ 129,452
Guarantee and commitment fees	3,489	3,213	7,422	6,908
Other income/(expense)	2,451	4,299	4,076	21,899
Total revenues	84,617	71,426	169,233	158,259
Release of/(provision for) losses	(1,073)	1,372	(1,620)	1,316
(Provision for)/release of reserve for losses	(69)	163	(272)	273
Operating expenses	(24,188)	(20,048)	(47,901)	(41,436)
Total non-interest expense	(24,257)	(19,885)	(48,173)	(41,163)
Core earnings before income taxes	59,287	52,913	119,440	118,412
Income tax (expense)/benefit	(12,075)	(11,058)	(25,193)	(25,104)
Core earnings before preferred stock dividends	47,212	41,855	94,247	93,308
Preferred stock dividends	(6,791)	(6,792)	(13,582)	(13,583)
Segment core earnings/(losses)	40,421	35,063	80,665	79,725
Total Assets	27,659,565	25,895,821	27,659,565	25,895,821	$ 27,333,110
Total on- and off-balance sheet program assets at principal balance	26,737,052	24,479,391	26,737,052	24,479,391
Reconciling Adjustments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0	0	0
Less: reconciling adjustments	(3,155)	2,968	(1,270)	10,667
Net effective spread	(3,155)	2,968	(1,270)	10,667
Guarantee and commitment fees	(1,092)	(1,496)	(1,813)	(2,358)
Other income/(expense)	2,042	3,992	2,600	21,078
Total revenues	(2,205)	5,464	(483)	29,387
Release of/(provision for) losses	0	0	0	0
(Provision for)/release of reserve for losses	0	0	0	0
Operating expenses	0	0	0	0
Total non-interest expense	0	0	0	0
Core earnings before income taxes	(2,205)	5,464	(483)	29,387
Income tax (expense)/benefit	464	(1,149)	102	(6,171)
Core earnings before preferred stock dividends	(1,741)	4,315	(381)	23,216
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	(1,741)	4,315	(381)	23,216
Total Assets	0	0	0	0
Total on- and off-balance sheet program assets at principal balance	0	0	0	0
Farm & Ranch
Segment Reporting Information, Profit (Loss) [Abstract]
Release of/(provision for) losses	(2)	610	109	533
Farm & Ranch | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	35,425	33,670	68,936	65,024
Less: reconciling adjustments	(1,037)	(1,080)	(2,083)	(2,080)
Net effective spread	34,388	32,590	66,853	62,944
Guarantee and commitment fees	4,221	4,338	8,513	8,554
Other income/(expense)	342	161	1,409	561
Total revenues	38,951	37,089	76,775	72,059
Release of/(provision for) losses	(5)	857	123	347
(Provision for)/release of reserve for losses	(75)	111	(652)	185
Operating expenses	0	0	0	0
Total non-interest expense	(75)	111	(652)	185
Core earnings before income taxes	38,871	38,057	76,246	72,591
Income tax (expense)/benefit	(8,163)	(7,991)	(16,012)	(15,243)
Core earnings before preferred stock dividends	30,708	30,066	60,234	57,348
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	30,708	30,066	60,234	57,348
Total Assets	14,456,296	13,686,589	14,456,296	13,686,589
Total on- and off-balance sheet program assets at principal balance	18,116,503	16,591,999	18,116,503	16,591,999
Corporate AgFinance
Segment Reporting Information, Profit (Loss) [Abstract]
Release of/(provision for) losses	(328)	(677)	(4,636)	(1,190)
Corporate AgFinance | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	7,444	6,929	14,592	14,138
Less: reconciling adjustments	0	0	0	0
Net effective spread	7,444	6,929	14,592	14,138
Guarantee and commitment fees	62	43	115	62
Other income/(expense)	12	143	12	257
Total revenues	7,518	7,115	14,719	14,457
Release of/(provision for) losses	(327)	(650)	(4,628)	(1,165)
(Provision for)/release of reserve for losses	0	0	0	0
Operating expenses	0	0	0	0
Total non-interest expense	0	0	0	0
Core earnings before income taxes	7,191	6,465	10,091	13,292
Income tax (expense)/benefit	(1,510)	(1,357)	(2,119)	(2,791)
Core earnings before preferred stock dividends	5,681	5,108	7,972	10,501
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	5,681	5,108	7,972	10,501
Total Assets	1,584,841	1,521,102	1,584,841	1,521,102
Total on- and off-balance sheet program assets at principal balance	1,680,756	1,567,311	1,680,756	1,567,311
Rural  Utilities | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	5,839	3,772	11,379	6,965
Less: reconciling adjustments	(31)	(39)	(64)	(73)
Net effective spread	5,808	3,733	11,315	6,892
Guarantee and commitment fees	281	308	562	620
Other income/(expense)	0	0	0	0
Total revenues	6,089	4,041	11,877	7,512
Release of/(provision for) losses	(632)	1,172	2,852	2,341
(Provision for)/release of reserve for losses	6	52	380	88
Operating expenses	0	0	0	0
Total non-interest expense	6	52	380	88
Core earnings before income taxes	5,463	5,265	15,109	9,941
Income tax (expense)/benefit	(1,147)	(1,105)	(3,173)	(2,087)
Core earnings before preferred stock dividends	4,316	4,160	11,936	7,854
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	4,316	4,160	11,936	7,854
Total Assets	6,169,811	5,632,551	6,169,811	5,632,551
Total on- and off-balance sheet program assets at principal balance	6,611,892	6,172,063	6,611,892	6,172,063
Renewable Energy | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	1,100	468	1,958	843
Less: reconciling adjustments	0	0	0	0
Net effective spread	1,100	468	1,958	843
Guarantee and commitment fees	17	20	45	30
Other income/(expense)	0	0	0	0
Total revenues	1,117	488	2,003	873
Release of/(provision for) losses	(110)	(8)	28	(210)
(Provision for)/release of reserve for losses	0	0	0	0
Operating expenses	0	0	0	0
Total non-interest expense	0	0	0	0
Core earnings before income taxes	1,007	480	2,031	663
Income tax (expense)/benefit	(211)	(101)	(426)	(139)
Core earnings before preferred stock dividends	796	379	1,605	524
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	796	379	1,605	524
Total Assets	314,538	126,513	314,538	126,513
Total on- and off-balance sheet program assets at principal balance	327,901	148,018	327,901	148,018
Funding | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	28,402	20,357	60,946	43,760
Less: reconciling adjustments	4,096	(1,849)	3,290	(8,514)
Net effective spread	32,498	18,508	64,236	35,246
Guarantee and commitment fees	0	0	0	0
Other income/(expense)	0	0	0	0
Total revenues	32,498	18,508	64,236	35,246
Release of/(provision for) losses	0	0	0	0
(Provision for)/release of reserve for losses	0	0	0	0
Operating expenses	0	0	0	0
Total non-interest expense	0	0	0	0
Core earnings before income taxes	32,498	18,508	64,236	35,246
Income tax (expense)/benefit	(6,825)	(3,887)	(13,490)	(7,402)
Core earnings before preferred stock dividends	25,673	14,621	50,746	27,844
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	25,673	14,621	50,746	27,844
Total Assets	0	0	0	0
Total on- and off-balance sheet program assets at principal balance	0	0	0	0
Investments | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	467	(1,282)	(76)	(1,278)
Less: reconciling adjustments	127	0	127	0
Net effective spread	594	(1,282)	51	(1,278)
Guarantee and commitment fees	0	0	0	0
Other income/(expense)	11	0	11	0
Total revenues	605	(1,282)	62	(1,278)
Release of/(provision for) losses	1	1	5	3
(Provision for)/release of reserve for losses	0	0	0	0
Operating expenses	0	0	0	0
Total non-interest expense	0	0	0	0
Core earnings before income taxes	606	(1,281)	67	(1,275)
Income tax (expense)/benefit	(127)	269	(14)	268
Core earnings before preferred stock dividends	479	(1,012)	53	(1,007)
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	479	(1,012)	53	(1,007)
Total Assets	4,959,243	4,781,990	4,959,243	4,781,990
Total on- and off-balance sheet program assets at principal balance	0	0	0	0
Corporate | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0	0	0
Less: reconciling adjustments	0	0	0	0
Net effective spread	0	0	0	0
Guarantee and commitment fees	0	0	0	0
Other income/(expense)	44	3	44	3
Total revenues	44	3	44	3
Release of/(provision for) losses	0	0	0	0
(Provision for)/release of reserve for losses	0	0	0	0
Operating expenses	(24,188)	(20,048)	(47,901)	(41,436)
Total non-interest expense	(24,188)	(20,048)	(47,901)	(41,436)
Core earnings before income taxes	(24,144)	(20,045)	(47,857)	(41,433)
Income tax (expense)/benefit	5,444	4,263	9,939	8,461
Core earnings before preferred stock dividends	(18,700)	(15,782)	(37,918)	(32,972)
Preferred stock dividends	(6,791)	(6,792)	(13,582)	(13,583)
Segment core earnings/(losses)	(25,491)	(22,574)	(51,500)	(46,555)
Total Assets	174,836	147,076	174,836	147,076
Total on- and off-balance sheet program assets at principal balance	$ 0	$ 0	$ 0	$ 0