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Disclosure - VARIABLE INTEREST ENTITIES - Narrative (Details) Sheet http://www.tristategt.org/role/VARIABLEINTERESTENTITIESNarrativeDetails VARIABLE INTEREST ENTITIES - Narrative (Details) Details 66 false false R67.htm 9954513 - Disclosure - VARIABLE INTEREST ENTITIES - Summary (Details) Sheet http://www.tristategt.org/role/VARIABLEINTERESTENTITIESSummaryDetails VARIABLE INTEREST ENTITIES - Summary (Details) Details 67 false false R68.htm 9954514 - Disclosure - LEGAL (Details) Sheet http://www.tristategt.org/role/LEGALDetails LEGAL (Details) Details http://www.tristategt.org/role/LEGAL 68 false false All Reports Book All Reports [DQC.US.0057.7494] One of the following elements Cash, CashAndCashEquivalentsAtCarryingValue, CashAndCashEquivalentsAtCarryingValueIncludingDiscontinuedOperations, CashAndDueFromBanks, CashCashEquivalentsAndFederalFundsSold, CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents, CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations, CashEquivalentsAtCarryingValue should appear as the opening and closing balance in the cash flow statement using the group http://www.tristategt.org/role/ConsolidatedStatementsofCashFlowsUnaudited. Instead the following balance items have been used in this statement CashCashEquivalentsRestrictedCashRestrictedCashEquivalentsAndInvestments. Depending if ASU-2016-18 has been adopted at least one of the opening and closing balance items listed must be used in the cash flow statement. - tris-20240331.xsd 556 - tris-20240331.xsd 556 [DQC.US.0057.9728] One of the following elements CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents, CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations should appear as the opening and closing balance in the cash flow statement using the group http://www.tristategt.org/role/ConsolidatedStatementsofCashFlowsUnaudited. Instead the following balance items have been used in this statement CashCashEquivalentsRestrictedCashRestrictedCashEquivalentsAndInvestments. Due to the implementaion of ASU-2016-18 at least one of the opening and closing balance items listed must be used in the cash flow statement. - tris-20240331.xsd 556 - tris-20240331.xsd 556 tris-20240331.htm tris-20240331.xsd tris-20240331_cal.xml tris-20240331_def.xml tris-20240331_lab.xml tris-20240331_pre.xml http://fasb.org/us-gaap/2023 http://xbrl.sec.gov/dei/2023 true true