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Basis of Presentation | 3 Months Ended
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Mar. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Basis of Presentation | The accompanying unaudited consolidated financial statements of First Interstate BancSystem, Inc., and its consolidated subsidiaries, including its wholly-owned subsidiary, First Interstate Bank (“FIB”) (collectively, the “Company”) contain all adjustments (all of which are of a normal recurring nature) necessary to present fairly the financial position of the Company at March 31, 2025 and December 31, 2024, the results of operations, changes in stockholders’ equity, and cash flows for each of the three months ended March 31, 2025 and 2024, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2024 is derived from audited consolidated financial statements. The unaudited consolidated financial statements have been prepared in conformity with the required interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X; and therefore, do not include all of the information and footnotes required by GAAP for a complete set of financial statements. Certain reclassifications, none of which were material, have been made to conform the Company’s prior year financial statements to the financial statements as of March 31, 2025. These reclassifications did not change previously reported net income, financial condition, cash flows, or stockholders’ equity. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, which includes a description of significant accounting policies. Operating results for the three months ended March 31, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025.

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- Definition The entire disclosure for the business description and basis of presentation concepts. Business description describes the nature and type of organization including but not limited to organizational structure as may be applicable to holding companies, parent and subsidiary relationships, business divisions, business units, business segments, affiliates and information about significant ownership of the reporting entity. Basis of presentation describes the underlying basis used to prepare the financial statements (for example, US Generally Accepted Accounting Principles, Other Comprehensive Basis of Accounting, IFRS). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 235 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org/235/tableOfContent Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 275 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org/275/tableOfContent Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 205 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org/205/tableOfContent + Details
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