Business Segment Reporting - Core Earnings (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			7
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	$ 87,643	$ 67,853	$ 245,378	$ 197,305
Guarantee and commitment fees	5,520	2,643	12,942	9,551
Other income/(expense)	3,940	1,382	8,016	23,281
Total revenues	97,103	71,878	266,336	230,137
Release of/(provision for) losses	136	(617)	(1,484)	699
Release of/(provision for) reserve for losses	45	167	(227)	440
Operating expenses	(24,034)	(19,379)	(71,935)	(60,815)
Total non-interest expense	(23,989)	(19,212)	(72,162)	(60,375)
Core earnings before income taxes	73,250	52,049	192,690	170,461
Income tax (expense)/benefit	(15,113)	(10,631)	(40,306)	(35,735)
Core earnings before preferred stock dividends	58,137	41,418	152,384	134,726
Preferred stock dividends	(6,792)	(6,791)	(20,374)	(20,374)
Segment core earnings/(losses)	51,345	34,627	132,010	114,352
Total Assets	28,311,381	26,441,588	28,311,381	26,441,588	$ 27,333,110
Total on- and off-balance sheet program assets at principal balance	27,652,011	25,326,638	27,652,011	25,326,638
Reconciling Adjustments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0	0	0
Less: reconciling adjustments	4,219	2,212	2,949	12,879
Net effective spread	4,219	2,212	2,949	12,879
Guarantee and commitment fees	692	(1,558)	(1,121)	(3,916)
Other income/(expense)	2,884	909	5,484	21,987
Total revenues	7,795	1,563	7,312	30,950
Release of/(provision for) losses	0	0	0	0
Release of/(provision for) 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	7,795	1,563	7,312	30,950
Income tax (expense)/benefit	(1,638)	(328)	(1,536)	(6,499)
Core earnings before preferred stock dividends	6,157	1,235	5,776	24,451
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	6,157	1,235	5,776	24,451
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	25	153	134	686
Farm & Ranch | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	33,735	34,173	102,671	99,197
Less: reconciling adjustments	(1,017)	(830)	(3,100)	(2,910)
Net effective spread	32,718	33,343	99,571	96,287
Guarantee and commitment fees	4,447	3,833	12,960	12,387
Other income/(expense)	807	469	2,216	1,030
Total revenues	37,972	37,645	114,747	109,704
Release of/(provision for) losses	13	93	136	440
Release of/(provision for) reserve for losses	58	139	(594)	324
Operating expenses	0	0	0	0
Total non-interest expense	58	139	(594)	324
Core earnings before income taxes	38,043	37,877	114,289	110,468
Income tax (expense)/benefit	(7,989)	(7,953)	(24,001)	(23,196)
Core earnings before preferred stock dividends	30,054	29,924	90,288	87,272
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	30,054	29,924	90,288	87,272
Total Assets	14,660,371	14,113,686	14,660,371	14,113,686
Total on- and off-balance sheet program assets at principal balance	18,461,835	17,199,347	18,461,835	17,199,347
Corporate AgFinance
Segment Reporting Information, Profit (Loss) [Abstract]
Release of/(provision for) losses	3,689	(334)	(947)	(1,524)
Corporate AgFinance | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	8,250	7,600	22,842	21,738
Less: reconciling adjustments	0	0	0	0
Net effective spread	8,250	7,600	22,842	21,738
Guarantee and commitment fees	78	46	193	108
Other income/(expense)	0	4	12	261
Total revenues	8,328	7,650	23,047	22,107
Release of/(provision for) losses	3,694	(333)	(934)	(1,498)
Release of/(provision for) 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	12,022	7,317	22,113	20,609
Income tax (expense)/benefit	(2,525)	(1,536)	(4,644)	(4,327)
Core earnings before preferred stock dividends	9,497	5,781	17,469	16,282
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	9,497	5,781	17,469	16,282
Total Assets	1,619,664	1,558,139	1,619,664	1,558,139
Total on- and off-balance sheet program assets at principal balance	1,741,306	1,634,786	1,741,306	1,634,786
Rural  Utilities | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	6,393	4,253	17,772	11,218
Less: reconciling adjustments	(31)	(33)	(95)	(106)
Net effective spread	6,362	4,220	17,677	11,112
Guarantee and commitment fees	279	309	841	929
Other income/(expense)	0	0	0	0
Total revenues	6,641	4,529	18,518	12,041
Release of/(provision for) losses	(3,504)	(414)	(652)	1,927
Release of/(provision for) reserve for losses	(13)	28	367	116
Operating expenses	0	0	0	0
Total non-interest expense	(13)	28	367	116
Core earnings before income taxes	3,124	4,143	18,233	14,084
Income tax (expense)/benefit	(656)	(869)	(3,829)	(2,956)
Core earnings before preferred stock dividends	2,468	3,274	14,404	11,128
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	2,468	3,274	14,404	11,128
Total Assets	6,648,693	5,779,300	6,648,693	5,779,300
Total on- and off-balance sheet program assets at principal balance	7,118,295	6,296,263	7,118,295	6,296,263
Renewable Energy | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	1,150	705	3,108	1,548
Less: reconciling adjustments	0	0	0	0
Net effective spread	1,150	705	3,108	1,548
Guarantee and commitment fees	24	13	69	43
Other income/(expense)	0	0	0	0
Total revenues	1,174	718	3,177	1,591
Release of/(provision for) losses	(66)	26	(38)	(184)
Release of/(provision for) 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	1,108	744	3,139	1,407
Income tax (expense)/benefit	(233)	(156)	(659)	(295)
Core earnings before preferred stock dividends	875	588	2,480	1,112
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	875	588	2,480	1,112
Total Assets	320,572	186,832	320,572	186,832
Total on- and off-balance sheet program assets at principal balance	330,575	196,242	330,575	196,242
Funding | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	37,642	23,913	98,588	67,673
Less: reconciling adjustments	(3,230)	(1,349)	60	(9,863)
Net effective spread	34,412	22,564	98,648	57,810
Guarantee and commitment fees	0	0	0	0
Other income/(expense)	3	0	3	0
Total revenues	34,415	22,564	98,651	57,810
Release of/(provision for) losses	0	0	0	0
Release of/(provision for) 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	34,415	22,564	98,651	57,810
Income tax (expense)/benefit	(7,226)	(4,739)	(20,716)	(12,141)
Core earnings before preferred stock dividends	27,189	17,825	77,935	45,669
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	27,189	17,825	77,935	45,669
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	473	(2,791)	397	(4,069)
Less: reconciling adjustments	59	0	186	0
Net effective spread	532	(2,791)	583	(4,069)
Guarantee and commitment fees	0	0	0	0
Other income/(expense)	6	0	17	0
Total revenues	538	(2,791)	600	(4,069)
Release of/(provision for) losses	(1)	11	4	14
Release of/(provision for) 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	537	(2,780)	604	(4,055)
Income tax (expense)/benefit	(113)	584	(127)	852
Core earnings before preferred stock dividends	424	(2,196)	477	(3,203)
Preferred stock dividends	0	0	0	0
Segment core earnings/(losses)	424	(2,196)	477	(3,203)
Total Assets	4,866,969	4,608,868	4,866,969	4,608,868
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)	240	0	284	3
Total revenues	240	0	284	3
Release of/(provision for) losses	0	0	0	0
Release of/(provision for) reserve for losses	0	0	0	0
Operating expenses	(24,034)	(19,379)	(71,935)	(60,815)
Total non-interest expense	(24,034)	(19,379)	(71,935)	(60,815)
Core earnings before income taxes	(23,794)	(19,379)	(71,651)	(60,812)
Income tax (expense)/benefit	5,267	4,366	15,206	12,827
Core earnings before preferred stock dividends	(18,527)	(15,013)	(56,445)	(47,985)
Preferred stock dividends	(6,792)	(6,791)	(20,374)	(20,374)
Segment core earnings/(losses)	(25,319)	(21,804)	(76,819)	(68,359)
Total Assets	195,112	194,763	195,112	194,763
Total on- and off-balance sheet program assets at principal balance	$ 0	$ 0	$ 0	$ 0