SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements of Investar Holding Corporation (the “Company”) have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include information or footnotes necessary for a complete presentation of financial position, results of operations, and cash flows in conformity with GAAP. However, in the opinion of management, all adjustments (consisting of normal recurring adjustments) necessary for a fair presentation of the financial statements have been included. The results of operations for the three month period ended March 31, 2015 are not necessarily indicative of the results that may be expected for the entire fiscal year. These statements should be read in conjunction with the Company’s audited consolidated financial statements for the year ended December 31, 2014, including the notes thereto, which were included as part of the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 31, 2015.
Nature of Operations	Nature of Operations Investar Holding Corporation, headquartered in Baton Rouge, Louisiana, provides full banking services, excluding trust services, through its wholly-owned banking subsidiary, Investar Bank (the “Bank”), a Louisiana-chartered bank. The Company’s primary market is South Louisiana. The Company currently operates 11 full service banking offices located throughout its market and had 177 employees at March 31, 2015.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, the Bank. All significant intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates, and such differences could be material. Material estimates that are susceptible to a significant change in the near term are the allowance for loan losses, the fair value of financial instruments and the determination of other-than-temporary impairments of securities.
Reclassifications	Reclassifications Certain reclassifications have been made to the 2014 financial statements to be consistent with the 2015 presentation.
Concentrations of Credit Risk	Concentrations of Credit Risk The Company’s loan portfolio consists of the various types of loans described in Note 4, Loans. Real estate or other assets secure most loans. The majority of loans has been made to individuals and businesses in the Company’s market of South Louisiana. Customers are dependent on the condition of the local economy for their livelihoods and servicing their loan obligations. The Company does not have any significant concentrations in any one industry or individual customer.
Recent Accounting Pronouncements	Recent Accounting Pronouncements FASB ASC Topic 835-30 “Interest-Imputation of Interest” Update No. 2015-03. The Financial Accounting Standards Board (the “FASB”) issued Update No. 2015-03 in April 2015 as part of its initiative to reduce complexity in the accounting standards. To simplify presentation of debt issuance costs, the amendments in this Update require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this Update. For public entities, the amendments in this Update are effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial position. FASB ASC Topic 810 “Consolidation” Update No. 2015-02. The FASB issued Update No. 2015-02 in February 2015 to respond to stakeholders’ concerns about the current accounting for consolidation of certain legal entities. The amendments in the update change the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities and are effective for public entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial position. FASB ASC Topic 225-20 “Income Statement – Extraordinary and Unusual Items” Update No. 2015-01. The FASB issued Update No. 2015-01 in January 2015 as part of its initiative to reduce complexity in accounting standards. This update eliminates from GAAP the concept of extraordinary items. The amendments in the update are effective for the annual period ending after December 15, 2015. Early adoption is permitted. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial position.

Disclosure of accounting policy for credit risk.

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Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting. The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.

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