Amount of investment in equity security without readily determinable fair value.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 320
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477268/942-320-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 320
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477268/942-320-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 320
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477268/942-320-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479536/321-10-50-3

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

INVESTMENTS IN OTHER ASSOCIATIONS (Details) - USD ($)	3 Months Ended
INVESTMENTS IN OTHER ASSOCIATIONS (Details) - USD ($)	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Equity Securities without Readily Determinable Fair Value [Line Items]
Investments in other associations	$ 193,561,000		$ 194,825,000
Impairment during the period	0	$ 0
Basin Electric Power Cooperative
Equity Securities without Readily Determinable Fair Value [Line Items]
Investments in other associations	142,457,000		142,457,000
National Rural Utilities Cooperative Finance Corporation - patronage capital
Equity Securities without Readily Determinable Fair Value [Line Items]
Investments in other associations	12,755,000		12,755,000
National Rural Utilities Cooperative Finance Corporation - capital term certificates
Equity Securities without Readily Determinable Fair Value [Line Items]
Investments in other associations	14,395,000		14,395,000
CoBank, ACB
Equity Securities without Readily Determinable Fair Value [Line Items]
Investments in other associations	18,846,000		20,050,000
Other
Equity Securities without Readily Determinable Fair Value [Line Items]
Investments in other associations	$ 5,108,000		$ 5,168,000