BUSINESS SEGMENT REPORTING - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2026	Mar. 31, 2026	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Segment Reporting [Line Items]
Interest income	$ 450,260		$ 399,022		$ 866,221	$ 780,436
(Interest expense)/benefit	(332,185)		(302,225)		(646,750)	(592,700)
Less: reconciling adjustments	(637)		(2,904)		(34)	(3,853)
Net effective spread	117,438		93,893		219,437	183,883
Guarantee and commitment fees	7,044		5,874		13,759	11,362
Other income/(expense)	896		680		1,715	1,924
Provision for losses	(7,369)		(7,812)		(12,196)	(9,395)
Operating expenses	(20,984)		(17,279)		(39,567)	(33,513)
Income tax expense	(20,376)		(15,825)		(38,262)	(32,394)
Segment core earnings	76,649		59,531		144,886	121,867
Reconciliation to net income:
Net effects of derivatives and trading securities	115		2,260		186	(275)
Unallocated (expenses)/income	(15,304)		(12,185)		(30,063)	(25,430)
Income tax effect related to reconciling items	5,491		5,231		11,065	8,326
Net income	66,951	$ 59,123	54,837	$ 49,651	126,074	104,488
Total on- and off-balance sheet segment assets at principal balance	37,197,138		30,587,259		37,197,138	30,587,259
Off-balance sheet assets under management	(6,026,228)		(5,257,348)		(6,026,228)	(5,257,348)
Unallocated assets	8,119,282		7,665,998		8,119,282	7,665,998
Total Assets	39,290,192		32,995,909		39,290,192	32,995,909	$ 35,370,157
Operating Segments | Farm & Ranch
Segment Reporting [Line Items]
Interest income	186,369		152,218		355,361	301,899
(Interest expense)/benefit	(145,286)		(115,524)		(275,677)	(230,313)
Net effective spread	40,063		35,710		77,736	69,595
Guarantee and commitment fees	4,968		4,551		9,920	9,102
Other income/(expense)	928		313		1,803	1,535
Provision for losses	(3,333)		(4,494)		(6,192)	(4,301)
Operating expenses	(9,286)		(7,020)		(17,451)	(13,615)
Income tax expense	(7,001)		(6,101)		(13,621)	(13,083)
Segment core earnings	26,339		22,959		52,195	49,233
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	21,987,822		18,217,905		21,987,822	18,217,905
Operating Segments | Corporate AgFinance
Segment Reporting [Line Items]
Interest income	33,344		25,484		58,513	50,606
(Interest expense)/benefit	(16,575)		(16,875)		(32,805)	(33,357)
Net effective spread	16,769		8,609		25,708	17,249
Guarantee and commitment fees	243		224		510	421
Other income/(expense)	15		345		15	345
Provision for losses	(524)		(614)		(2,544)	(1,442)
Operating expenses	(2,356)		(2,378)		(4,836)	(4,511)
Income tax expense	(2,971)		(1,300)		(3,959)	(2,535)
Segment core earnings	11,176		4,886		14,894	9,527
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	2,082,762		1,953,523		2,082,762	1,953,523
Operating Segments | Power & Utilities
Segment Reporting [Line Items]
Interest income	76,362		67,447		150,226	132,442
(Interest expense)/benefit	(69,377)		(61,786)		(136,707)	(121,424)
Net effective spread	6,962		5,636		13,453	10,965
Guarantee and commitment fees	196		215		396	436
Other income/(expense)	0		0		0	0
Provision for losses	(368)		(73)		(307)	(150)
Operating expenses	(1,258)		(1,156)		(2,355)	(2,279)
Income tax expense	(1,162)		(970)		(2,350)	(1,883)
Segment core earnings	4,370		3,652		8,837	7,089
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	8,266,639		7,300,354		8,266,639	7,300,354
Operating Segments | Broadband Infrastructure
Segment Reporting [Line Items]
Interest income	18,006		12,159		34,130	22,992
(Interest expense)/benefit	(11,428)		(8,227)		(21,724)	(15,494)
Net effective spread	6,578		3,932		12,406	7,498
Guarantee and commitment fees	1,081		564		1,956	900
Other income/(expense)	(25)		0		(81)	0
Provision for losses	(1,987)		(666)		(1,940)	(437)
Operating expenses	(1,881)		(1,274)		(3,586)	(2,326)
Income tax expense	(790)		(537)		(1,838)	(1,184)
Segment core earnings	2,976		2,019		6,917	4,451
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,851,902		1,174,441		1,851,902	1,174,441
Operating Segments | Renewable Energy
Segment Reporting [Line Items]
Interest income	35,893		23,494		67,852	43,809
(Interest expense)/benefit	(25,120)		(17,267)		(48,000)	(32,470)
Net effective spread	10,773		6,227		19,852	11,339
Guarantee and commitment fees	556		320		977	503
Other income/(expense)	(22)		8		(22)	8
Provision for losses	(1,157)		(1,964)		(1,213)	(3,064)
Operating expenses	(2,221)		(1,560)		(4,111)	(3,268)
Income tax expense	(1,665)		(637)		(3,251)	(1,159)
Segment core earnings	6,264		2,394		12,232	4,359
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	3,008,013		1,941,036		3,008,013	1,941,036
Operating Segments | Funding
Segment Reporting [Line Items]
Interest income	17,968		35,619		37,171	68,597
(Interest expense)/benefit	16,855		(1,920)		28,967	(3,380)
Net effective spread	35,229		31,668		67,876	63,272
Guarantee and commitment fees	0		0		0	0
Other income/(expense)	0		0		0	0
Provision for losses	0		0		0	0
Operating expenses	(2,969)		(3,003)		(5,391)	(5,803)
Income tax expense	(6,776)		(6,020)		(13,123)	(12,069)
Segment core earnings	25,484		22,645		49,362	45,400
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	0		0		0	0
Operating Segments | Investments
Segment Reporting [Line Items]
Interest income	82,318		82,601		162,968	160,091
(Interest expense)/benefit	(81,254)		(80,626)		(160,804)	(156,262)
Net effective spread	1,064		2,111		2,406	3,965
Guarantee and commitment fees	0		0		0	0
Other income/(expense)	0		14		0	36
Provision for losses	0		(1)		0	(1)
Operating expenses	(1,013)		(888)		(1,837)	(1,711)
Income tax expense	(11)		(260)		(120)	(481)
Segment core earnings	40		976		449	1,808
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 [Line Items]
Less: reconciling adjustments	(1,020)		(984)		(1,948)	(1,991)
Reconciling Adjustments | Corporate AgFinance
Segment Reporting [Line Items]
Less: reconciling adjustments	0		0		0	0
Reconciling Adjustments | Power & Utilities
Segment Reporting [Line Items]
Less: reconciling adjustments	(23)		(25)		(66)	(53)
Reconciling Adjustments | Broadband Infrastructure
Segment Reporting [Line Items]
Less: reconciling adjustments	0		0		0	0
Reconciling Adjustments | Renewable Energy
Segment Reporting [Line Items]
Less: reconciling adjustments	0		0		0	0
Reconciling Adjustments | Funding
Segment Reporting [Line Items]
Less: reconciling adjustments	406		(2,031)		1,738	(1,945)
Reconciling Adjustments | Investments
Segment Reporting [Line Items]
Less: reconciling adjustments	$ 0		$ 136		$ 242	$ 136