BUSINESS SEGMENT REPORTING - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Interest income	$ 1,612,247	$ 1,603,516	$ 1,392,288
Interest expense	(1,221,513)	(1,249,649)	(1,064,741)
Less: reconciling adjustments	(7,693)	(14,303)	(567)
Net effective spread	383,041	339,564	326,980
Guarantee and commitment fees	23,792	20,321	18,928
Other income/(expense)	2,162	2,188	3,019
(Provision for)/release of losses	(32,913)	(11,490)	(1,136)
Operating expenses	(69,361)	(59,404)	(52,417)
Income tax (expense)/benefit	(64,410)	(61,148)	(62,029)
Segment core earnings	242,311	230,031	233,345
Reconciliation to net income:
Net effects of derivatives and trading securities	(679)	13,141	1,954
Unallocated (expenses)/income	(50,331)	(46,217)	(44,227)
Income tax effect related to reconciling items	16,114	10,238	8,931
Net income	207,415	207,193	200,003
Total on- and off-balance sheet segment assets at principal balance	33,351,569	29,523,030	28,471,024
Off-balance sheet assets under management	(5,765,446)	(4,981,285)	(4,710,199)
Unallocated assets	7,784,034	6,782,997	5,763,557
Total Assets	35,370,157	31,324,742	29,524,382
Operating Segments | Farm & Ranch
Segment Reporting Information [Line Items]
Interest income	614,331	615,016	559,730
Interest expense	(469,656)	(475,248)	(422,651)
Net effective spread	140,615	135,310	132,900
Guarantee and commitment fees	18,224	17,695	17,415
Other income/(expense)	1,849	3,167	2,952
(Provision for)/release of losses	(8,619)	(1,147)	(507)
Operating expenses	(27,664)	(24,741)	(23,306)
Income tax (expense)/benefit	(26,120)	(27,360)	(27,183)
Segment core earnings	98,285	102,924	102,271
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	19,564,916	18,606,968	18,808,801
Operating Segments | Corporate AgFinance
Segment Reporting Information [Line Items]
Interest income	102,439	100,820	92,335
Interest expense	(67,542)	(70,695)	(61,111)
Net effective spread	34,897	30,125	31,224
Guarantee and commitment fees	917	571	283
Other income/(expense)	440	(2,055)	35
(Provision for)/release of losses	(15,325)	(6,850)	(207)
Operating expenses	(10,372)	(7,905)	(5,540)
Income tax (expense)/benefit	(2,220)	(2,916)	(5,418)
Segment core earnings	8,337	10,970	20,377
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,950,536	1,887,705	1,693,979
Operating Segments | Power & Utilities
Segment Reporting Information [Line Items]
Interest income	273,500	260,636	232,106
Interest expense	(250,362)	(240,600)	(215,763)
Net effective spread	23,034	19,987	16,175
Guarantee and commitment fees	850	966	1,090
Other income/(expense)	(7)	0	0
(Provision for)/release of losses	84	274	4,117
Operating expenses	(4,575)	(4,281)	(3,553)
Income tax (expense)/benefit	(4,069)	(3,559)	(3,746)
Segment core earnings	15,317	13,387	14,083
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	7,860,622	6,809,366	6,979,570
Operating Segments | Broadband Infrastructure
Segment Reporting Information [Line Items]
Interest income	52,109	38,225	30,299
Interest expense	(34,622)	(27,282)	(21,455)
Net effective spread	17,487	10,943	8,844
Guarantee and commitment fees	2,452	464	43
Other income/(expense)	0	0	0
(Provision for)/release of losses	(5,505)	1,469	(4,324)
Operating expenses	(5,103)	(3,666)	(2,415)
Income tax (expense)/benefit	(1,960)	(1,934)	(453)
Segment core earnings	7,371	7,276	1,695
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,532,206	802,466	501,153
Operating Segments | Renewable Energy
Segment Reporting Information [Line Items]
Interest income	104,276	54,188	18,923
Interest expense	(76,212)	(40,471)	(14,275)
Net effective spread	28,064	13,717	4,648
Guarantee and commitment fees	1,349	625	97
Other income/(expense)	8	0	0
(Provision for)/release of losses	(3,574)	(5,236)	(219)
Operating expenses	(6,633)	(4,848)	(3,382)
Income tax (expense)/benefit	(4,035)	(894)	(238)
Segment core earnings	15,179	3,364	906
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	2,443,289	1,416,525	487,521
Operating Segments | Funding
Segment Reporting Information [Line Items]
Interest income	137,024	224,390	200,264
Interest expense	(1,523)	(89,698)	(71,849)
Net effective spread	131,743	124,896	132,009
Guarantee and commitment fees	0	0	0
Other income/(expense)	0	0	3
(Provision for)/release of losses	0	0	0
Operating expenses	(11,644)	(10,855)	(11,037)
Income tax (expense)/benefit	(25,222)	(23,949)	(25,405)
Segment core earnings	94,877	90,092	95,570
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	0	0	0
Operating Segments | Investments
Segment Reporting Information [Line Items]
Interest income	328,568	310,241	258,631
Interest expense	(321,596)	(305,655)	(257,637)
Net effective spread	7,201	4,586	1,180
Guarantee and commitment fees	0	0	0
Other income/(expense)	(128)	1,076	29
(Provision for)/release of losses	26	0	4
Operating expenses	(3,370)	(3,108)	(3,184)
Income tax (expense)/benefit	(784)	(536)	414
Segment core earnings	2,945	2,018	(1,557)
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	0	0	0
Reconciling Adjustments | Farm & Ranch
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(4,060)	(4,458)	(4,179)
Reconciling Adjustments | Corporate AgFinance
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0	0	0
Reconciling Adjustments | Power & Utilities
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(104)	(49)	(168)
Reconciling Adjustments | Broadband Infrastructure
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0	0	0
Reconciling Adjustments | Renewable Energy
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0	0	0
Reconciling Adjustments | Funding
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(3,758)	(9,796)	3,594
Reconciling Adjustments | Investments
Segment Reporting Information [Line Items]
Less: reconciling adjustments	$ 229	$ 0	$ 186