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Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of agreements entered into among the reporting persons, the issuer, and other stockholders of the issuer signatory thereto, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported therein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with James R. Scott with the indication of direct or indirect ownership in Tables I and II being made from James R. 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The reporting persons disclaim beneficial ownership of any such securities, except to the extent of their pecuniary interests therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Julie Scott Rose with the indication of direct or indirect ownership in Table I and Table II being made from Julie Scott Rose's perspective. 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The restricted stock units vest in three equal annual installments beginning on September 14, 2027, subject to the reporting person's continued employment through each applicable vesting date."}],"balance_after":5417,"source":{"system":"sec-edgar","filing":"0002154828-26-000005","document":"wk-form4_1789578965.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/2154828/000215482826000005/wk-form4_1789578965.xml","form_type":"4"}},{"id":4617515,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-09-14T23:21:32.000Z","date":"2026-09-14","kind":"sale","planned":false,"acquired":false,"shares":8071,"price":37.29,"value":300967.59,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $37.10 to $37.44. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 453,200 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 sharesheld of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 461,271 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 sharesheld of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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The reporting persons disclaim beneficial ownership of any such securities, except to the extent of their pecuniary interests therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Julie Scott Rose with the indication of direct or indirect ownership in Table I and Table II being made from Julie Scott Rose's perspective. 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These shares were sold in multiple transactions at prices ranging from $40.12 to $40.57. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 478,200 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 sharesheld of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Julie Scott Rose with the indication of direct or indirect ownership in Table I and Table II being made from Julie Scott Rose's perspective. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Julie Scott Rose with the indication of direct or indirect ownership in Table I and Table II being made from Julie Scott Rose's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":493359,"source":{"system":"sec-edgar","filing":"0001493152-26-029403","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315226029403/ownership.xml","form_type":"4"}},{"id":732868,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":28392,"kind":"person","name":"SCOTT JULIE A","position":1,"cik":"0001234619","reported_name":"SCOTT JULIE A","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28393,"kind":"organization","name":"Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002","position":2,"cik":"0001908851","reported_name":"Julie A Scott Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-2002","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":3,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28395,"kind":"organization","name":"Juliana Sarah Scott Rose Trust","position":4,"cik":"0001909078","reported_name":"Juliana Sarah Scott Rose Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28396,"kind":"organization","name":"Elizabeth Lauren Scott Rose Trust","position":5,"cik":"0001908961","reported_name":"Elizabeth Lauren Scott Rose Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-06-18T21:51:22.000Z","date":"2026-06-18","kind":"sale","planned":false,"acquired":false,"shares":5000,"price":35.95,"value":179750.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"Composed of 218,216 shares held of record by Julie A Scott-Rose Trustee of the Julie A Scott Rose Trust Dated 5-14-02, 35,233 shares held of record by Juliana Sarah Scott Rose Trust, 35,232 shares held of record by Elizabeth Lauren Scott Rose Trust, and 209,678 shares held by IXL Limited Liability Company, over which Ms. Rose has shared voting and dispositive power with a sibling."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F4","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Julie Scott Rose with the indication of direct or indirect ownership in Table I and Table II being made from Julie Scott Rose's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":498359,"source":{"system":"sec-edgar","filing":"0001493152-26-029403","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315226029403/ownership.xml","form_type":"4"}},{"id":732867,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-06-18T19:46:45.000Z","date":"2026-06-18","kind":"sale","planned":false,"acquired":false,"shares":9390,"price":36.11,"value":339072.9,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $36.00 to $36.33. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 488,200 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 sharesheld of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":852738,"source":{"system":"sec-edgar","filing":"0001493152-26-029300","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315226029300/ownership.xml","form_type":"4"}},{"id":732866,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-06-18T14:23:30.000Z","date":"2026-06-17","kind":"sale","planned":false,"acquired":false,"shares":4500,"price":36.29,"value":163305.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from\n$36.01 to $36.45. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First\nInterstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the\nnumber of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 497,590 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678\nshares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares\nheld of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of\nrecord by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the\nIssuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share\nbeneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such\nsecurities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any,\ntogether with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R.\nScott's perspective. 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These shares were sold in multiple transactions at prices ranging from $35.43 to $35.74. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 502,090 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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The restricted stock units vest on June 1, 2027, subject to the reporting persons provision of continuous service to the Registrant through the earlier of the applicable vesting date or the date of the Registrant's next annual shareholder meeting."}],"balance_after":4126,"source":{"system":"sec-edgar","filing":"0001199246-26-000002","document":"wk-form4_1780509006.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000119924626000002/wk-form4_1780509006.xml","form_type":"4"}},{"id":753264,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42039,"kind":"person","name":"Shepler Christopher L.","position":1,"cik":"0002090710","reported_name":"Shepler Christopher L.","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Banking Officer"}}],"security":"Common Stock","published_at":"2026-06-03T17:50:03.000Z","date":"2026-06-01","kind":"grant","planned":false,"acquired":true,"shares":3370,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vests on June 1, 2029, subject to the reporting person's continued employment through the vesting date."}],"balance_after":13240,"source":{"system":"sec-edgar","filing":"0002090710-26-000004","document":"wk-form4_1780509000.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000209071026000004/wk-form4_1780509000.xml","form_type":"4"}},{"id":753265,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42040,"kind":"person","name":"Meyer Lori","position":1,"cik":"0002003084","reported_name":"Meyer Lori","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"EVP, Chief Information Officer"}}],"security":"Common Stock","published_at":"2026-06-03T17:49:57.000Z","date":"2026-06-01","kind":"grant","planned":false,"acquired":true,"shares":2247,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vests on June 1, 2029, subject to the reporting person's continued employment through the vesting date."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F2","text":"The number of shares reported herein reflects a correction to the reporting persons beneficial ownership. A Form 4 filed on March 18, 2026 incorrectly reported that 1,550 shares of common stock were withheld to satisfy tax withholding obligations upon vesting of a previously reported restricted stock award. The correct number of shares withheld for such purpose was 813."}],"balance_after":16517,"source":{"system":"sec-edgar","filing":"0002003084-26-000006","document":"wk-form4_1780508994.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000200308426000006/wk-form4_1780508994.xml","form_type":"4"}},{"id":753263,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42038,"kind":"person","name":"Cho Alice S","position":1,"cik":"0001812520","reported_name":"Cho Alice S","relationship":{"director":true,"officer":false,"ten_percent_owner":false,"other":false}}],"security":"Common Stock","published_at":"2026-06-03T17:49:52.000Z","date":"2026-06-01","kind":"grant","planned":false,"acquired":true,"shares":2247,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. 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The reporting person disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"Reportable beneficial ownership acquired upon receipt of shares by gift by the reporting person of general partner interests in NBAR5 O Limited Partnership, which partnership holds such shares directly and with respect to which the reporting person previously held only limited partner interests. The reporting person disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein."}],"balance_after":236808,"source":{"system":"sec-edgar","filing":"0001493152-26-007141","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315226007141/ownership.xml","form_type":"5"}},{"id":903422,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42028,"kind":"person","name":"Scott Jeremy","position":1,"cik":"0001803925","reported_name":"Scott Jeremy","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66334,"kind":"organization","name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","position":2,"cik":"0001909124","reported_name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66335,"kind":"organization","name":"NBAR5 Limited Partnership","position":3,"cik":"0002076804","reported_name":"NBAR5 Limited Partnership","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-17T21:30:16.000Z","date":"2025-12-08","kind":"gift","planned":false,"acquired":true,"shares":550,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"See footnote"},"footnotes":[{"field":"shares","element":"transactionShares","label":"F2","text":"Composed of 3,416,108 shares held of record by NBar5 Limited Partnership, 25,119 shares held of record by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 (550 of which were received as a gift on August 8, 2025 but inadvertently previously reported incorrectly as held directly), 68,942 shares held of record by Jeremy Scott Trustee, 2025 Grantor Retained Annuity Irrevocable Trust, and 3,380 shares held of record by Jeremy Scott's spouse (550 of which were received as a gift as described in the table)."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F2","text":"Composed of 3,416,108 shares held of record by NBar5 Limited Partnership, 25,119 shares held of record by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 (550 of which were received as a gift on August 8, 2025 but inadvertently previously reported incorrectly as held directly), 68,942 shares held of record by Jeremy Scott Trustee, 2025 Grantor Retained Annuity Irrevocable Trust, and 3,380 shares held of record by Jeremy Scott's spouse (550 of which were received as a gift as described in the table)."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of agreements entered into among the reporting persons, the issuer, and other stockholders of the issuer signatory thereto, the reporting persons may be deemed members of a group with the other signatories to the agreement and may be deemed to share beneficial ownership of the securities to which this footnote relates. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":3513549,"source":{"system":"sec-edgar","filing":"0001493152-26-007143","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315226007143/ownership.xml","form_type":"5"}},{"id":903421,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42028,"kind":"person","name":"Scott Jeremy","position":1,"cik":"0001803925","reported_name":"Scott Jeremy","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66334,"kind":"organization","name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","position":2,"cik":"0001909124","reported_name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66335,"kind":"organization","name":"NBAR5 Limited Partnership","position":3,"cik":"0002076804","reported_name":"NBAR5 Limited Partnership","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-17T21:30:16.000Z","date":"2025-08-04","kind":"gift","planned":false,"acquired":true,"shares":236808,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"See footnote"},"footnotes":[{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F1","text":"Reportable beneficial ownership acquired upon receipt of shares by gift by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 of general partner interests in NBAR5 O Limited Partnership, which partnership holds such shares directly and with respect to which the reporting persons, as applicable, previously held only limited partner interests. The reporting persons disclaim beneficial ownership of such shares except to the extent of his or its pecuniary interest therein."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"Reportable beneficial ownership acquired upon receipt of shares by gift by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15 of general partner interests in NBAR5 O Limited Partnership, which partnership holds such shares directly and with respect to which the reporting persons, as applicable, previously held only limited partner interests. The reporting persons disclaim beneficial ownership of such shares except to the extent of his or its pecuniary interest therein."}],"balance_after":236808,"source":{"system":"sec-edgar","filing":"0001493152-26-007143","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315226007143/ownership.xml","form_type":"5"}},{"id":948770,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-06T23:50:55.000Z","date":"2026-01-06","kind":"sale","planned":false,"acquired":false,"shares":1827,"price":36.92,"value":67452.84,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $36.42 to $37.15. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F4","text":"Composed of 571,486 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F5","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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These shares were sold in multiple transactions at prices ranging from $36.10 to $36.37. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"Composed of 573,313 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F5","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Risa K Scott."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 322,546 shares held of record by Risa K. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Susan Scott Heyneman, Trust."}],"balance_after":224460,"source":{"system":"sec-edgar","filing":"0001493152-25-025519","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225025519/ownership.xml","form_type":"4"}},{"id":989337,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42027,"kind":"person","name":"HEYNEMAN JOHN M JR","position":1,"cik":"0001198518","reported_name":"HEYNEMAN JOHN M JR","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":72614,"kind":"organization","name":"John M Heyneman Jr. Trust","position":2,"cik":"0001908848","reported_name":"John M Heyneman Jr. Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":72615,"kind":"organization","name":"Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust","position":3,"cik":"0001908849","reported_name":"Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":72616,"kind":"organization","name":"Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust","position":4,"cik":"0001908784","reported_name":"Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":72617,"kind":"organization","name":"Towanda Investments Limited Partnership","position":5,"cik":"0001908810","reported_name":"Towanda Investments Limited Partnership","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-11-25T17:29:24.000Z","date":"2025-11-21","kind":"sale","planned":false,"acquired":false,"shares":30432,"price":31.03,"value":944304.96,"ownership":{"direct":false,"nature":"see footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 150,000 shares held of record by John M Heyneman Jr. Trust, 85,836 shares held of record by Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust, 85,836 shares held of record by Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust, 1,085,792 shares held of record by Towanda Investments Limited Partnership, 4,552 shares held of record by John Heyneman, Jr.'s spouse, 1095 shares held of record by John Heyneman, Jr.'s daughter, 1,215 shares held of record by John Heyneman, Jr.'s son Quinn, and 310 shares held of record by John Heyneman, Jr.'s son Bae-John."}],"balance_after":1414636,"source":{"system":"sec-edgar","filing":"0001198518-25-000009","document":"wk-form4_1764091760.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000119851825000009/wk-form4_1764091760.xml","form_type":"4"}},{"id":990661,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42039,"kind":"person","name":"Shepler Christopher L.","position":1,"cik":"0002090710","reported_name":"Shepler Christopher L.","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Banking Officer"}}],"security":"Common Stock","published_at":"2025-11-24T18:52:45.000Z","date":"2025-11-24","kind":"grant","planned":false,"acquired":true,"shares":1591,"price":31.42,"value":49989.22,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest in three equal annual\ninstallments beginning on November 24, 2026, subject to the reporting person's continued employment through each applicable vesting date."}],"balance_after":3899,"source":{"system":"sec-edgar","filing":"0002090710-25-000010","document":"wk-form4_1764010362.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000209071025000010/wk-form4_1764010362.xml","form_type":"4"}},{"id":1003021,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42027,"kind":"person","name":"HEYNEMAN JOHN M JR","position":1,"cik":"0001198518","reported_name":"HEYNEMAN JOHN M JR","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-11-12T21:46:11.000Z","date":"2025-11-11","kind":"sale","planned":false,"acquired":false,"shares":15000,"price":32.14,"value":482100.0,"ownership":{"direct":false,"nature":"By Bench Ranch LLC"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":30154,"source":{"system":"sec-edgar","filing":"0001198518-25-000004","document":"wk-form4_1762983968.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/860413/000119851825000004/wk-form4_1762983968.xml","form_type":"4"}},{"id":1003020,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42027,"kind":"person","name":"HEYNEMAN JOHN M JR","position":1,"cik":"0001198518","reported_name":"HEYNEMAN JOHN M JR","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-11-12T21:46:11.000Z","date":"2025-11-10","kind":"sale","planned":false,"acquired":false,"shares":20000,"price":32.06,"value":641200.0,"ownership":{"direct":false,"nature":"By Awe' LLC"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":67482,"source":{"system":"sec-edgar","filing":"0001198518-25-000004","document":"wk-form4_1762983968.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/860413/000119851825000004/wk-form4_1762983968.xml","form_type":"4"}},{"id":1003018,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42027,"kind":"person","name":"HEYNEMAN JOHN M JR","position":1,"cik":"0001198518","reported_name":"HEYNEMAN JOHN M JR","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-11-12T21:46:11.000Z","date":"2025-09-10","kind":"other","planned":false,"acquired":true,"shares":45154,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"By Bench Ranch LLC"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":45154,"source":{"system":"sec-edgar","filing":"0001198518-25-000004","document":"wk-form4_1762983968.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/860413/000119851825000004/wk-form4_1762983968.xml","form_type":"4"}},{"id":1003017,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42027,"kind":"person","name":"HEYNEMAN JOHN M JR","position":1,"cik":"0001198518","reported_name":"HEYNEMAN JOHN M JR","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-11-12T21:46:11.000Z","date":"2025-09-09","kind":"other","planned":false,"acquired":true,"shares":30432,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"see footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 180,432 shares held of record by John M Heyneman Jr. Trust, 85,836 shares held of record by Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust, 85,836 shares held of record by Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust, 1,085,792 shares held of record by Towanda Investments Limited Partnership, 4,552 shares held of record by John Heyneman, Jr.'s spouse, 1,095 shares held of record by John Heyneman, Jr.'s daughter, 1,215 shares held of record by John Heyneman, Jr.'s son Quinn, and 310 shares held of record by John Heyneman, Jr.'s son Bae-John."}],"balance_after":1445068,"source":{"system":"sec-edgar","filing":"0001198518-25-000004","document":"wk-form4_1762983968.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000119851825000004/wk-form4_1762983968.xml","form_type":"4"}},{"id":1010173,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-11-04T00:56:51.000Z","date":"2025-11-03","kind":"sale","planned":false,"acquired":false,"shares":4800,"price":31.27,"value":150096.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"Composed of 576,486 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 45,200 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Susan Scott Heyneman, Trust."}],"balance_after":234460,"source":{"system":"sec-edgar","filing":"0001493152-25-020651","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225020651/ownership.xml","form_type":"4"}},{"id":1012256,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-29T23:02:21.000Z","date":"2025-10-29","kind":"sale","planned":false,"acquired":false,"shares":7000,"price":32.09,"value":224630.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.00 to $32.64. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 576,486 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. 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The restricted stock units vest in three equal annual installments beginning on September 10, 2026, subject to the reporting person's continued employment through each applicable vesting date."}],"balance_after":2308,"source":{"system":"sec-edgar","filing":"0002090710-25-000007","document":"wk-form4_1760047225.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000209071025000007/wk-form4_1760047225.xml","form_type":"4"}},{"id":1021085,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-09T19:23:20.000Z","date":"2025-10-09","kind":"sale","planned":false,"acquired":false,"shares":685,"price":31.66,"value":21687.1,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.52 to $31.76. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 589,086 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":952824,"source":{"system":"sec-edgar","filing":"0001493152-25-017566","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225017566/ownership.xml","form_type":"4"}},{"id":1021838,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-09T01:07:23.000Z","date":"2025-10-08","kind":"sale","planned":false,"acquired":false,"shares":5600,"price":32.01,"value":179256.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.00 to $32.07. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F5","text":"Composed of 584,171 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse."}],"balance_after":953509,"source":{"system":"sec-edgar","filing":"0001493152-25-017493","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225017493/ownership.xml","form_type":"4"}},{"id":1021837,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":30197,"kind":"person","name":"Scott Jonathan R","position":1,"cik":"0001361935","reported_name":"Scott Jonathan R","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30198,"kind":"organization","name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","position":2,"cik":"0001908962","reported_name":"Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30199,"kind":"organization","name":"Harrison William Scott Trust","position":3,"cik":"0001908873","reported_name":"Harrison William Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30200,"kind":"organization","name":"Harper Grace Scott Trust","position":4,"cik":"0001908895","reported_name":"Harper Grace Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":30201,"kind":"organization","name":"Holland Elizabeth Scott Trust","position":5,"cik":"0001908953","reported_name":"Holland Elizabeth Scott Trust","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":28394,"kind":"organization","name":"IXL Ltd Liability Co","position":6,"cik":"0001909090","reported_name":"IXL Ltd Liability Co","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-09T01:07:23.000Z","date":"2025-10-07","kind":"sale","planned":false,"acquired":false,"shares":13715,"price":32.09,"value":440114.35,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.00 to $32.33. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon, request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Composed of 589,771 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 36,553 shares held of record by Holland Elizabeth Scott Trust, 36,553 shares held of record by Harper Grace Scott Trust, 36,554 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":959109,"source":{"system":"sec-edgar","filing":"0001493152-25-017493","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225017493/ownership.xml","form_type":"4"}},{"id":1025816,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":72454,"kind":"organization","name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","position":1,"cik":"0001908880","reported_name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-03T17:25:12.000Z","date":"2025-10-01","kind":"sale","planned":false,"acquired":false,"shares":10000,"price":31.59,"value":315900.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F1","text":"Composed of 244,460 shares held of record by Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Susan Scott Heyneman, Trust."}],"balance_after":244460,"source":{"system":"sec-edgar","filing":"0001493152-25-016804","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225016804/ownership.xml","form_type":"4"}},{"id":1025815,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":72454,"kind":"organization","name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","position":1,"cik":"0001908880","reported_name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-03T17:25:12.000Z","date":"2025-09-17","kind":"other","planned":false,"acquired":false,"shares":67482,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Susan Scott Heyneman, Trust."}],"balance_after":254460,"source":{"system":"sec-edgar","filing":"0001493152-25-016804","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225016804/ownership.xml","form_type":"4"}},{"id":1025814,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":72454,"kind":"organization","name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","position":1,"cik":"0001908880","reported_name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-03T17:25:12.000Z","date":"2025-09-10","kind":"other","planned":false,"acquired":false,"shares":45154,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Susan Scott Heyneman, Trust."}],"balance_after":321942,"source":{"system":"sec-edgar","filing":"0001493152-25-016804","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225016804/ownership.xml","form_type":"4"}},{"id":1025813,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":72454,"kind":"organization","name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","position":1,"cik":"0001908880","reported_name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-10-03T17:25:12.000Z","date":"2025-09-09","kind":"other","planned":false,"acquired":false,"shares":152160,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Susan Scott Heyneman, Trust."}],"balance_after":367096,"source":{"system":"sec-edgar","filing":"0001493152-25-016804","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000149315225016804/ownership.xml","form_type":"4"}},{"id":1045336,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42031,"kind":"person","name":"Agrawal Renu","position":1,"cik":"0001838577","reported_name":"Agrawal Renu","relationship":{"director":true,"officer":false,"ten_percent_owner":false,"other":false}}],"security":"Common Stock","published_at":"2025-09-09T16:19:25.000Z","date":"2025-09-05","kind":"grant","planned":false,"acquired":true,"shares":1827,"price":32.83,"value":59980.41,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest on June 1, 2026,\nsubject to the reporting person's provision of continuous service to the Registrant through the vesting date."}],"balance_after":1827,"source":{"system":"sec-edgar","filing":"0000860413-25-000145","document":"wk-form4_1757434761.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000086041325000145/wk-form4_1757434761.xml","form_type":"4"}},{"id":1047177,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42028,"kind":"person","name":"Scott Jeremy","position":1,"cik":"0001803925","reported_name":"Scott Jeremy","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66334,"kind":"organization","name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","position":2,"cik":"0001909124","reported_name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66335,"kind":"organization","name":"NBAR5 Limited Partnership","position":3,"cik":"0002076804","reported_name":"NBAR5 Limited Partnership","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-09-06T01:39:13.000Z","date":"2025-08-05","kind":"other","planned":false,"acquired":true,"shares":216,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"see footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"Composed of 3,416,108 shares held of record by NBar5 Limited Partnership, 93,511 shares held of record following both transactions reported herein by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15, and 2,830 shares held of record by Jeremy Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of agreements entered into among the reporting persons, the issuer, and other stockholders of the issuer signatory thereto, the reporting persons may be deemed members of a group with the other signatories to the agreement and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":3512449,"source":{"system":"sec-edgar","filing":"0001641172-25-026792","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/860413/000164117225026792/ownership.xml","form_type":"4"}},{"id":1047176,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42028,"kind":"person","name":"Scott Jeremy","position":1,"cik":"0001803925","reported_name":"Scott Jeremy","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66334,"kind":"organization","name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","position":2,"cik":"0001909124","reported_name":"Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":66335,"kind":"organization","name":"NBAR5 Limited Partnership","position":3,"cik":"0002076804","reported_name":"NBAR5 Limited Partnership","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-09-06T01:39:13.000Z","date":"2025-09-03","kind":"gift","planned":false,"acquired":true,"shares":22928,"price":0,"value":0.0,"ownership":{"direct":false,"nature":"see footnote"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F1","text":"Composed of 3,416,108 shares held of record by NBar5 Limited Partnership, 93,511 shares held of record following both transactions reported herein by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15, and 2,830 shares held of record by Jeremy Scott's spouse."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of agreements entered into among the reporting persons, the issuer, and other stockholders of the issuer signatory thereto, the reporting persons may be deemed members of a group with the other signatories to the agreement and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons."}],"balance_after":3512233,"source":{"system":"sec-edgar","filing":"0001641172-25-026792","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000164117225026792/ownership.xml","form_type":"4"}},{"id":1052222,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":72454,"kind":"organization","name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","position":1,"cik":"0001908880","reported_name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-09-02T19:47:45.000Z","date":"2025-09-02","kind":"sale","planned":false,"acquired":false,"shares":10000,"price":32.28,"value":322800.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F1","text":"Composed of 519,256 shares held of record by Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4, if any, together with Susan Scott Heyneman, Trust."}],"balance_after":519256,"source":{"system":"sec-edgar","filing":"0001641172-25-026204","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000164117225026204/ownership.xml","form_type":"4"}},{"id":1053214,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":42041,"kind":"person","name":"SCUDDER MICHAEL L","position":1,"cik":"0001199246","reported_name":"SCUDDER MICHAEL L","relationship":{"director":true,"officer":false,"ten_percent_owner":false,"other":false}}],"security":"Common Stock","published_at":"2025-08-29T17:05:06.000Z","date":"2025-08-27","kind":"grant","planned":false,"acquired":true,"shares":1879,"price":31.93,"value":59996.47,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. 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These shares were sold in multiple transactions at prices ranging from $30.07 to $30.23.  The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holder of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon request, the full information regarding the number of shares sold at each separate price within the ranges set forth above."}],"balance_after":5224,"source":{"system":"sec-edgar","filing":"0000860413-25-000125","document":"wk-form4_1755554830.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/860413/000086041325000125/wk-form4_1755554830.xml","form_type":"4"}},{"id":1077944,"issuer":{"id":4141,"kind":"organization","name":"FIRST INTERSTATE BANCSYSTEM INC","symbol":"FIBK"},"owners":[{"id":72454,"kind":"organization","name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","position":1,"cik":"0001908880","reported_name":"Susan Scott Heyneman Trust, Susan Heyneman & First Interstate Wealth Management Co-Trustees","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-08-01T20:17:54.000Z","date":"2025-08-01","kind":"sale","planned":false,"acquired":false,"shares":55000,"price":27.86,"value":1532300.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in column 4 is a weighted-average price. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. 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Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. 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