BUSINESS SEGMENT REPORTING - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Interest income	$ 381,414	$ 396,317
Interest expense	(290,475)	(309,949)
Less: reconciling adjustments	(949)	(3,324)
Net effective spread	89,990	83,044
Guarantee and commitment fees	5,488	4,982
Other income/(expense)	1,244	1,011
Release of/(provision for) losses	(1,583)	1,870
Operating expenses	(16,234)	(14,298)
Income tax (expense)/benefit	(16,569)	(16,088)
Segment core earnings	62,336	60,521
Reconciliation to net income:
Net effects of derivatives and trading securities	(2,535)	4,479
Unallocated (expenses)/income	(13,245)	(12,842)
Income tax effect related to reconciling items	3,095	1,588
Net income	49,651	53,746
Total on- and off-balance sheet segment assets at principal balance	29,755,343	28,847,230
Off-balance sheet assets under management	(5,071,733)	(4,637,247)
Unallocated assets	7,120,329	5,562,208
Total Assets	31,803,939	29,772,191	$ 31,324,742
Operating Segments | Farm & Ranch
Segment Reporting Information [Line Items]
Interest income	149,681	152,204
Interest expense	(114,789)	(118,315)
Net effective spread	33,885	32,843
Guarantee and commitment fees	4,551	4,484
Other income/(expense)	1,222	995
Release of/(provision for) losses	193	(497)
Operating expenses	(6,595)	(6,129)
Income tax (expense)/benefit	(6,982)	(6,656)
Segment core earnings	26,274	25,040
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	18,094,515	18,900,906
Operating Segments | Corporate AgFinance
Segment Reporting Information [Line Items]
Interest income	25,122	24,888
Interest expense	(16,482)	(16,917)
Net effective spread	8,640	7,971
Guarantee and commitment fees	197	87
Other income/(expense)	0	12
Release of/(provision for) losses	(828)	378
Operating expenses	(2,133)	(1,850)
Income tax (expense)/benefit	(1,235)	(1,386)
Segment core earnings	4,641	5,212
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,889,363	1,766,294
Operating Segments | Power & Utilities
Segment Reporting Information [Line Items]
Interest income	64,995	66,306
Interest expense	(59,638)	(61,383)
Net effective spread	5,329	4,890
Guarantee and commitment fees	221	256
Other income/(expense)	0	0
Release of/(provision for) losses	(77)	174
Operating expenses	(1,123)	(1,131)
Income tax (expense)/benefit	(913)	(880)
Segment core earnings	3,437	3,309
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	7,187,966	6,970,538
Operating Segments | Broadband Infrastructure
Segment Reporting Information [Line Items]
Interest income	10,833	8,695
Interest expense	(7,267)	(6,353)
Net effective spread	3,566	2,342
Guarantee and commitment fees	336	93
Other income/(expense)	0	0
Release of/(provision for) losses	229	2,836
Operating expenses	(1,052)	(827)
Income tax (expense)/benefit	(647)	(933)
Segment core earnings	2,432	3,511
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	974,835	467,185
Operating Segments | Renewable Energy
Segment Reporting Information [Line Items]
Interest income	20,315	8,149
Interest expense	(15,203)	(6,100)
Net effective spread	5,112	2,049
Guarantee and commitment fees	183	62
Other income/(expense)	0	0
Release of/(provision for) losses	(1,100)	(1,022)
Operating expenses	(1,708)	(1,068)
Income tax (expense)/benefit	(522)	(4)
Segment core earnings	1,965	17
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	1,608,664	742,307
Operating Segments | Funding
Segment Reporting Information [Line Items]
Interest income	32,978	60,239
Interest expense	(1,460)	(25,520)
Net effective spread	31,604	32,474
Guarantee and commitment fees	0	0
Other income/(expense)	0	0
Release of/(provision for) losses	0	0
Operating expenses	(2,800)	(2,564)
Income tax (expense)/benefit	(6,049)	(6,281)
Segment core earnings	22,755	23,629
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	0	0
Operating Segments | Investments
Segment Reporting Information [Line Items]
Interest income	77,490	75,836
Interest expense	(75,636)	(75,361)
Net effective spread	1,854	475
Guarantee and commitment fees	0	0
Other income/(expense)	22	4
Release of/(provision for) losses	0	1
Operating expenses	(823)	(729)
Income tax (expense)/benefit	(221)	52
Segment core earnings	832	(197)
Reconciliation to net income:
Total on- and off-balance sheet segment assets at principal balance	0	0
Reconciling Adjustments | Farm & Ranch
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(1,007)	(1,046)
Reconciling Adjustments | Corporate AgFinance
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0	0
Reconciling Adjustments | Power & Utilities
Segment Reporting Information [Line Items]
Less: reconciling adjustments	(28)	(33)
Reconciling Adjustments | Broadband Infrastructure
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0	0
Reconciling Adjustments | Renewable Energy
Segment Reporting Information [Line Items]
Less: reconciling adjustments	0	0
Reconciling Adjustments | Funding
Segment Reporting Information [Line Items]
Less: reconciling adjustments	86	(2,245)
Reconciling Adjustments | Investments
Segment Reporting Information [Line Items]
Less: reconciling adjustments	$ 0	$ 0