BUSINESS SEGMENT REPORTING - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Interest income	$ 399,022		$ 403,706		$ 780,436	$ 800,023
Interest expense	(302,225)		(316,366)		(592,700)	(626,315)
Less: reconciling adjustments	(2,904)		(3,744)		(3,853)	(7,068)
Net effective spread	93,893		83,596		183,883	166,640
Guarantee and commitment fees	5,874		5,256		11,362	10,238
Other income/(expense)	680		424		1,924	1,435
(Provision for)/release of losses	(7,812)		(6,230)		(9,395)	(4,360)
Operating expenses	(17,279)		(13,838)		(33,513)	(28,136)
Income tax (expense)/benefit	(15,825)		(14,536)		(32,394)	(30,624)
Segment core earnings	59,531		54,672		121,867	115,193
Reconciliation to net income:
Net effects of derivatives and trading securities	2,260		653		(275)	5,132
Unallocated (expenses)/income	(12,185)		(10,643)		(25,430)	(23,485)
Income tax effect related to reconciling items	5,231		2,423		8,326	4,011
Net income	54,837	$ 49,651	47,105	$ 53,746	104,488	100,851
Total on- and off-balance sheet segment assets at principal balance	30,587,259		28,758,339		30,587,259	28,758,339
Off-balance sheet assets under management	(5,257,348)		(4,569,607)		(5,257,348)	(4,569,607)
Unallocated assets	7,665,998		6,005,582		7,665,998	6,005,582
Total Assets	32,995,909		30,194,314		32,995,909	30,194,314	$ 31,324,742
Operating Segments | Farm & Ranch
Segment Reporting Information [Line Items]
Interest income	152,218		157,317		301,899	309,521
Interest expense	(115,524)		(121,795)		(230,313)	(240,110)
Net effective spread	35,710		34,156		69,595	66,999
Guarantee and commitment fees	4,551		4,612		9,102	9,096
Other income/(expense)	313		517		1,535	1,512
(Provision for)/release of losses	(4,494)		(247)		(4,301)	(744)
Operating expenses	(7,020)		(5,866)		(13,615)	(11,995)
Income tax (expense)/benefit	(6,101)		(6,967)		(13,083)	(13,623)
Segment core earnings	22,959		26,205		49,233	51,245
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	18,217,905		18,504,501		18,217,905	18,504,501
Operating Segments | Corporate AgFinance
Segment Reporting Information [Line Items]
Interest income	25,484		26,036		50,606	50,924
Interest expense	(16,875)		(18,170)		(33,357)	(35,087)
Net effective spread	8,609		7,866		17,249	15,837
Guarantee and commitment fees	224		127		421	214
Other income/(expense)	345		(1,152)		345	(1,140)
(Provision for)/release of losses	(614)		(5,354)		(1,442)	(4,976)
Operating expenses	(2,378)		(1,905)		(4,511)	(3,755)
Income tax (expense)/benefit	(1,300)		88		(2,535)	(1,298)
Segment core earnings	4,886		(330)		9,527	4,882
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,953,523		1,816,893		1,953,523	1,816,893
Operating Segments | Power & Utilities
Segment Reporting Information [Line Items]
Interest income	67,447		67,375		132,442	133,681
Interest expense	(61,786)		(62,096)		(121,424)	(123,479)
Net effective spread	5,636		5,253		10,965	10,142
Guarantee and commitment fees	215		245		436	501
Other income/(expense)	0		0		0	0
(Provision for)/release of losses	(73)		116		(150)	290
Operating expenses	(1,156)		(1,016)		(2,279)	(2,147)
Income tax (expense)/benefit	(970)		(966)		(1,883)	(1,846)
Segment core earnings	3,652		3,632		7,089	6,940
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	7,300,354		7,008,275		7,300,354	7,008,275
Operating Segments | Broadband Infrastructure
Segment Reporting Information [Line Items]
Interest income	12,159		8,728		22,992	17,423
Interest expense	(8,227)		(6,335)		(15,494)	(12,688)
Net effective spread	3,932		2,393		7,498	4,735
Guarantee and commitment fees	564		56		900	149
Other income/(expense)	0		0		0	0
(Provision for)/release of losses	(666)		371		(437)	3,207
Operating expenses	(1,274)		(893)		(2,326)	(1,720)
Income tax (expense)/benefit	(537)		(405)		(1,184)	(1,338)
Segment core earnings	2,019		1,522		4,451	5,033
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,174,441		553,198		1,174,441	553,198
Operating Segments | Renewable Energy
Segment Reporting Information [Line Items]
Interest income	23,494		11,600		43,809	19,749
Interest expense	(17,267)		(8,601)		(32,470)	(14,701)
Net effective spread	6,227		2,999		11,339	5,048
Guarantee and commitment fees	320		216		503	278
Other income/(expense)	8		0		8	0
(Provision for)/release of losses	(1,964)		(1,117)		(3,064)	(2,139)
Operating expenses	(1,560)		(1,186)		(3,268)	(2,254)
Income tax (expense)/benefit	(637)		(192)		(1,159)	(196)
Segment core earnings	2,394		720		4,359	737
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,941,036		875,472		1,941,036	875,472
Operating Segments | Funding
Segment Reporting Information [Line Items]
Interest income	35,619		56,845		68,597	117,084
Interest expense	(1,920)		(24,225)		(3,380)	(49,745)
Net effective spread	31,668		30,268		63,272	62,743
Guarantee and commitment fees	0		0		0	0
Other income/(expense)	0		0		0	0
(Provision for)/release of losses	0		0		0	0
Operating expenses	(3,003)		(2,318)		(5,803)	(4,882)
Income tax (expense)/benefit	(6,020)		(5,870)		(12,069)	(12,151)
Segment core earnings	22,645		22,080		45,400	45,710
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	0		0		0	0
Operating Segments | Investments
Segment Reporting Information [Line Items]
Interest income	82,601		75,805		160,091	151,641
Interest expense	(80,626)		(75,144)		(156,262)	(150,505)
Net effective spread	2,111		661		3,965	1,136
Guarantee and commitment fees	0		0		0	0
Other income/(expense)	14		1,059		36	1,063
(Provision for)/release of losses	(1)		1		(1)	2
Operating expenses	(888)		(654)		(1,711)	(1,383)
Income tax (expense)/benefit	(260)		(224)		(481)	(172)
Segment core earnings	976		843		1,808	646
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	0		0		0	0
Reconciling Adjustments | Farm & Ranch
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(984)		(1,366)		(1,991)	(2,412)
Reconciling Adjustments | Corporate AgFinance
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0		0		0	0
Reconciling Adjustments | Power & Utilities
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(25)		(26)		(53)	(60)
Reconciling Adjustments | Broadband Infrastructure
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0		0		0	0
Reconciling Adjustments | Renewable Energy
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0		0		0	0
Reconciling Adjustments | Funding
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(2,031)		(2,352)		(1,945)	(4,596)
Reconciling Adjustments | Investments
Segment Reporting Information [Line Items]
Less: reconciling adjustments	$ 136		$ 0		$ 136	$ 0