Business Segment Reporting - Core Earnings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment	7
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	$ 270,940	$ 221,951	$ 195,848
Guarantee and commitment fees	13,040	12,669	12,549
Gain on the sale of mortgage loans	0	6,539	0
Other income/(expense)	25,131	2,531	5,744
Total revenues	309,111	243,690	214,141
(Provision for)/release of losses	(1,323)	860	(7,805)
Release of/(provision for) reserve for losses	517	1,327	(250)
Operating expenses	(82,626)	(73,416)	(61,403)
Total non-interest expense	(82,109)	(72,089)	(61,653)
Core earnings before income taxes	225,679	172,461	144,683
Income tax (expense)/benefit	(47,535)	(36,372)	(30,307)
Core earnings before preferred stock dividends	178,144	136,089	114,376
Preferred stock dividends	(27,165)	(24,677)	(17,805)
Loss on retirement of preferred stock			(1,667)
Segment core earnings/(losses)	150,979	111,412	94,904
Total Assets	27,333,110	25,121,009	24,330,328
Total on- and off-balance sheet program assets at principal balance	25,922,082	23,614,463	21,924,095
Reconciling Adjustments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0	0
Less: reconciling adjustments	15,411	1,283	(1,108)
Net Effective Spread	15,411	1,283	(1,108)
Guarantee and commitment fees	(5,104)	(4,864)	(6,601)
Gain on the sale of mortgage loans		0
Other income/(expense)	23,447	851	2,594
Total revenues	33,754	(2,730)	(5,115)
(Provision for)/release of losses	0	0	0
Release of/(provision for) reserve for losses	0	0	0
Operating expenses	0	0	0
Total non-interest expense	0	0	0
Core earnings before income taxes	33,754	(2,730)	(5,115)
Income tax (expense)/benefit	(7,089)	572	1,074
Core earnings before preferred stock dividends	26,665	(2,158)	(4,041)
Preferred stock dividends	0	0	0
Loss on retirement of preferred stock			(1,667)
Segment core earnings/(losses)	26,665	(2,158)	(5,708)
Total Assets	0	0	0
Total on- and off-balance sheet program assets at principal balance	0	0	0
Farm & Ranch
Segment Reporting Information, Profit (Loss) [Abstract]
(Provision for)/release of losses	(1,246)	1,576	(3,068)
Farm & Ranch | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	133,218	118,289	96,355
Less: reconciling adjustments	(4,161)	(4,753)	(6,197)
Net Effective Spread	129,057	113,536	90,158
Guarantee and commitment fees	16,718	16,178	17,800
Gain on the sale of mortgage loans		6,539
Other income/(expense)	1,420	1,966	3,652
Total revenues	147,195	138,219	111,610
(Provision for)/release of losses	(1,463)	1,574	(2,941)
Release of/(provision for) reserve for losses	247	1,034	(80)
Operating expenses	(819)	0	0
Total non-interest expense	(572)	1,034	(80)
Core earnings before income taxes	145,160	140,827	108,589
Income tax (expense)/benefit	(30,482)	(29,574)	(22,802)
Core earnings before preferred stock dividends	114,678	111,253	85,787
Preferred stock dividends	0	0	0
Loss on retirement of preferred stock			0
Segment core earnings/(losses)	114,678	111,253	85,787
Total Assets	14,623,596	13,112,193	12,373,781
Total on- and off-balance sheet program assets at principal balance	17,728,792	16,094,640	14,872,894
Corporate AgFinance
Segment Reporting Information, Profit (Loss) [Abstract]
(Provision for)/release of losses	(2,171)	(219)	109
Corporate AgFinance | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	29,209	27,081	21,441
Less: reconciling adjustments	0	0	0
Net Effective Spread	29,209	27,081	21,441
Guarantee and commitment fees	139	48	5
Gain on the sale of mortgage loans		0
Other income/(expense)	261	0	0
Total revenues	29,609	27,129	21,446
(Provision for)/release of losses	(2,136)	(210)	36
Release of/(provision for) reserve for losses	0	0	0
Operating expenses	0	0	0
Total non-interest expense	0	0	0
Core earnings before income taxes	27,473	26,919	21,482
Income tax (expense)/benefit	(5,768)	(5,653)	(4,511)
Core earnings before preferred stock dividends	21,705	21,266	16,971
Preferred stock dividends	0	0	0
Loss on retirement of preferred stock			0
Segment core earnings/(losses)	21,705	21,266	16,971
Total Assets	1,541,151	1,507,848	1,663,581
Total on- and off-balance sheet program assets at principal balance	1,603,507	1,537,834	1,664,115
Rural  Utilities | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	16,175	8,224	7,083
Less: reconciling adjustments	(103)	(157)	(207)
Net Effective Spread	16,072	8,067	6,876
Guarantee and commitment fees	1,238	1,287	1,345
Gain on the sale of mortgage loans		0
Other income/(expense)	0	5	32
Total revenues	17,310	9,359	8,253
(Provision for)/release of losses	2,751	(291)	(4,763)
Release of/(provision for) reserve for losses	270	293	(170)
Operating expenses	0	0	0
Total non-interest expense	270	293	(170)
Core earnings before income taxes	20,331	9,361	3,320
Income tax (expense)/benefit	(4,268)	(1,965)	(697)
Core earnings before preferred stock dividends	16,063	7,396	2,623
Preferred stock dividends	0	0	0
Loss on retirement of preferred stock			0
Segment core earnings/(losses)	16,063	7,396	2,623
Total Assets	5,867,517	5,344,707	4,760,585
Total on- and off-balance sheet program assets at principal balance	6,359,613	5,895,226	5,314,051
Renewable Energy | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	2,483	1,219	303
Less: reconciling adjustments	0	0	0
Net Effective Spread	2,483	1,219	303
Guarantee and commitment fees	49	20	0
Gain on the sale of mortgage loans		0
Other income/(expense)	0	0	0
Total revenues	2,532	1,239	303
(Provision for)/release of losses	(494)	(198)	(110)
Release of/(provision for) reserve for losses	0	0	0
Operating expenses	0	0	0
Total non-interest expense	0	0	0
Core earnings before income taxes	2,038	1,041	193
Income tax (expense)/benefit	(428)	(219)	(41)
Core earnings before preferred stock dividends	1,610	822	152
Preferred stock dividends	0	0	0
Loss on retirement of preferred stock			0
Segment core earnings/(losses)	1,610	822	152
Total Assets	219,609	87,553	73,493
Total on- and off-balance sheet program assets at principal balance	230,170	86,763	73,035
Funding | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	96,613	66,581	71,706
Less: reconciling adjustments	(11,147)	3,627	7,512
Net Effective Spread	85,466	70,208	79,218
Guarantee and commitment fees	0	0	0
Gain on the sale of mortgage loans		0
Other income/(expense)	0	0	0
Total revenues	85,466	70,208	79,218
(Provision for)/release of losses	0	0	0
Release of/(provision for) reserve for losses	0	0	0
Operating expenses	0	0	0
Total non-interest expense	0	0	0
Core earnings before income taxes	85,466	70,208	79,218
Income tax (expense)/benefit	(17,949)	(14,744)	(16,636)
Core earnings before preferred stock dividends	67,517	55,464	62,582
Preferred stock dividends	0	0	0
Loss on retirement of preferred stock			0
Segment core earnings/(losses)	67,517	55,464	62,582
Total Assets	0	0	0
Total on- and off-balance sheet program assets at principal balance	0	0	0
Investments | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	(6,758)	557	(1,040)
Less: reconciling adjustments	0	0	0
Net Effective Spread	(6,758)	557	(1,040)
Guarantee and commitment fees	0	0	0
Gain on the sale of mortgage loans		0
Other income/(expense)	0	0	0
Total revenues	(6,758)	557	(1,040)
(Provision for)/release of losses	19	(15)	(27)
Release of/(provision for) reserve for losses	0	0	0
Operating expenses	0	0	0
Total non-interest expense	0	0	0
Core earnings before income taxes	(6,739)	542	(1,067)
Income tax (expense)/benefit	1,416	(114)	224
Core earnings before preferred stock dividends	(5,323)	428	(843)
Preferred stock dividends	0	0	0
Loss on retirement of preferred stock			0
Segment core earnings/(losses)	(5,323)	428	(843)
Total Assets	4,806,010	5,012,827	5,415,596
Total on- and off-balance sheet program assets at principal balance	0	0	0
Corporate | Operating Segments
Segment Reporting Information, Profit (Loss) [Abstract]
Net interest income	0	0	0
Less: reconciling adjustments	0	0	0
Net Effective Spread	0	0	0
Guarantee and commitment fees	0	0	0
Gain on the sale of mortgage loans		0
Other income/(expense)	3	(291)	(534)
Total revenues	3	(291)	(534)
(Provision for)/release of losses	0	0	0
Release of/(provision for) reserve for losses	0	0	0
Operating expenses	(81,807)	(73,416)	(61,403)
Total non-interest expense	(81,807)	(73,416)	(61,403)
Core earnings before income taxes	(81,804)	(73,707)	(61,937)
Income tax (expense)/benefit	17,033	15,325	13,082
Core earnings before preferred stock dividends	(64,771)	(58,382)	(48,855)
Preferred stock dividends	(27,165)	(24,677)	(17,805)
Loss on retirement of preferred stock			0
Segment core earnings/(losses)	(91,936)	(83,059)	(66,660)
Total Assets	275,227	55,881	43,292
Total on- and off-balance sheet program assets at principal balance	$ 0	$ 0	$ 0