Business Segment Reporting - Core Earnings (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) segment	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			7
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	$ 67,853	$ 58,916	$ 197,305	$ 168,115
Guarantee and commitment fees	2,643	3,155	9,551	9,182
Other income/(expense)	1,382	(16)	23,281	4,396
Total revenues	71,878	62,055	230,137	181,693
Release of/(provision for) losses	(617)	(366)	699	(518)
Release of reserve for losses	167	111	440	1,277
Operating expenses	(19,379)	(17,107)	(60,815)	(52,866)
Total non-interest expense	(19,212)	(16,996)	(60,375)	(51,589)
Core earnings before income taxes	52,049	44,693	170,461	129,586
Income tax (expense)/benefit	(10,631)	(9,388)	(35,735)	(27,350)
Core earnings before preferred stock dividends	41,418	35,305	134,726	102,236
Preferred stock dividends	(6,791)	(6,774)	(20,374)	(17,885)
Loss on retirement of preferred stock		0	114,352	84,351
Segment core earnings/(losses)	34,627	28,531
Total Assets	26,441,588	24,744,368	26,441,588	24,744,368	$ 25,121,009
Total on- and off-balance sheet program assets at principal balance	25,326,638	23,118,791	25,326,638	23,118,791
Reconciling Adjustments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0	0	0
Less: reconciling adjustments	2,212	2,991	12,879	1,780
Net Effective Spread	2,212	2,991	12,879	1,780
Guarantee and commitment fees	(1,558)	(1,167)	(3,916)	(3,714)
Other income/(expense)	909	(703)	21,987	2,957
Total revenues	1,563	1,121	30,950	1,023
Release of/(provision for) losses	0	0	0	0
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	1,563	1,121	30,950	1,023
Income tax (expense)/benefit	(328)	(236)	(6,499)	(215)
Core earnings before preferred stock dividends	1,235	885	24,451	808
Preferred stock dividends	0	0	0	0
Loss on retirement of preferred stock		0	24,451	808
Segment core earnings/(losses)	1,235	885
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		(400)
Farm & Ranch | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	34,173	30,063	99,197	88,186
Less: reconciling adjustments	(830)	(1,148)	(2,910)	(3,647)
Net Effective Spread	33,343	28,915	96,287	84,539
Guarantee and commitment fees	3,833	3,988	12,387	11,906
Other income/(expense)	469	557	1,030	1,560
Total revenues	37,645	33,460	109,704	98,005
Release of/(provision for) losses	93	(261)	440	322
Release of reserve for losses	139	91	324	996
Operating expenses	0	0	0	0
Total non-interest expense	139	91	324	996
Core earnings before income taxes	37,877	33,290	110,468	99,323
Income tax (expense)/benefit	(7,953)	(6,991)	(23,196)	(20,857)
Core earnings before preferred stock dividends	29,924	26,299	87,272	78,466
Preferred stock dividends	0	0	0	0
Loss on retirement of preferred stock		0	87,272	78,466
Segment core earnings/(losses)	29,924	26,299
Total Assets	14,113,686	12,845,105	14,113,686	12,845,105
Total on- and off-balance sheet program assets at principal balance	17,199,347	15,565,589	17,199,347	15,565,589
Corporate AgFinance | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	7,600	7,162	21,738	20,760
Less: reconciling adjustments	0	0	0	0
Net Effective Spread	7,600	7,162	21,738	20,760
Guarantee and commitment fees	46	9	108	18
Other income/(expense)	4	0	261	0
Total revenues	7,650	7,171	22,107	20,778
Release of/(provision for) losses	(333)	(191)	(1,498)	(157)
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	7,317	6,980	20,609	20,621
Income tax (expense)/benefit	(1,536)	(1,466)	(4,327)	(4,330)
Core earnings before preferred stock dividends	5,781	5,514	16,282	16,291
Preferred stock dividends	0	0	0	0
Loss on retirement of preferred stock		0	16,282	16,291
Segment core earnings/(losses)	5,781	5,514
Total Assets	1,558,139	1,347,182	1,558,139	1,347,182
Total on- and off-balance sheet program assets at principal balance	1,634,786	1,379,816	1,634,786	1,379,816
Rural  Utilities | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	4,253	2,101	11,218	5,648
Less: reconciling adjustments	(33)	(34)	(106)	(102)
Net Effective Spread	4,220	2,067	11,112	5,546
Guarantee and commitment fees	309	325	929	958
Other income/(expense)	0	2	0	4
Total revenues	4,529	2,394	12,041	6,508
Release of/(provision for) losses	(414)	45	1,927	(490)
Release of reserve for losses	28	20	116	281
Operating expenses	0	0	0	0
Total non-interest expense	28	20	116	281
Core earnings before income taxes	4,143	2,459	14,084	6,299
Income tax (expense)/benefit	(869)	(516)	(2,956)	(1,322)
Core earnings before preferred stock dividends	3,274	1,943	11,128	4,977
Preferred stock dividends	0	0	0	0
Loss on retirement of preferred stock		0	11,128	4,977
Segment core earnings/(losses)	3,274	1,943
Total Assets	5,779,300	5,511,782	5,779,300	5,511,782
Total on- and off-balance sheet program assets at principal balance	6,296,263	6,080,691	6,296,263	6,080,691
Renewable Energy | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	705	237	1,548	863
Less: reconciling adjustments	0	0	0	0
Net Effective Spread	705	237	1,548	863
Guarantee and commitment fees	13	0	43	14
Other income/(expense)	0	0	0	0
Total revenues	718	237	1,591	877
Release of/(provision for) losses	26	35	(184)	(177)
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	744	272	1,407	700
Income tax (expense)/benefit	(156)	(57)	(295)	(147)
Core earnings before preferred stock dividends	588	215	1,112	553
Preferred stock dividends	0	0	0	0
Loss on retirement of preferred stock		0	1,112	553
Segment core earnings/(losses)	588	215
Total Assets	186,832	88,738	186,832	88,738
Total on- and off-balance sheet program assets at principal balance	196,242	92,695	196,242	92,695
Funding | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	23,913	19,195	67,673	52,260
Less: reconciling adjustments	(1,349)	(1,809)	(9,863)	1,969
Net Effective Spread	22,564	17,386	57,810	54,229
Guarantee and commitment fees	0	0	0	0
Other income/(expense)	0	0	0	0
Total revenues	22,564	17,386	57,810	54,229
Release of/(provision for) losses	0	0	0	0
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	22,564	17,386	57,810	54,229
Income tax (expense)/benefit	(4,739)	(3,651)	(12,141)	(11,388)
Core earnings before preferred stock dividends	17,825	13,735	45,669	42,841
Preferred stock dividends	0	0	0	0
Loss on retirement of preferred stock		0	45,669	42,841
Segment core earnings/(losses)	17,825	13,735
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	(2,791)	158	(4,069)	398
Less: reconciling adjustments	0	0	0	0
Net Effective Spread	(2,791)	158	(4,069)	398
Guarantee and commitment fees	0	0	0	0
Other income/(expense)	0	0	0	0
Total revenues	(2,791)	158	(4,069)	398
Release of/(provision for) losses	11	6	14	(16)
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	(2,780)	164	(4,055)	382
Income tax (expense)/benefit	584	(35)	852	(80)
Core earnings before preferred stock dividends	(2,196)	129	(3,203)	302
Preferred stock dividends	0	0	0	0
Loss on retirement of preferred stock		0	(3,203)	302
Segment core earnings/(losses)	(2,196)	129
Total Assets	4,608,868	4,919,431	4,608,868	4,919,431
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)	0	128	3	(125)
Total revenues	0	128	3	(125)
Release of/(provision for) losses	0	0	0	0
Release of reserve for losses	0	0	0	0
Operating expenses	(19,379)	(17,107)	(60,815)	(52,866)
Total non-interest expense	(19,379)	(17,107)	(60,815)	(52,866)
Core earnings before income taxes	(19,379)	(16,979)	(60,812)	(52,991)
Income tax (expense)/benefit	4,366	3,564	12,827	10,989
Core earnings before preferred stock dividends	(15,013)	(13,415)	(47,985)	(42,002)
Preferred stock dividends	(6,791)	(6,774)	(20,374)	(17,885)
Loss on retirement of preferred stock		0	(68,359)	(59,887)
Segment core earnings/(losses)	(21,804)	(20,189)
Total Assets	194,763	32,130	194,763	32,130
Total on- and off-balance sheet program assets at principal balance	$ 0	$ 0	$ 0	$ 0