SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Jun. 30, 2016
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 and six month periods ended June 30, 2016 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, 2015, 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 11, 2016.
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 10 full service banking offices located throughout its market and had 152 employees at June 30, 2016.
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 statements in conformity with U.S. 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 particularly susceptible to significant change relate to the determination of the allowance for loan losses. While management uses available information to recognize losses on loans, future additions to the allowance may be necessary based on changes in local economic conditions. In addition, regulatory agencies, as an integral part of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to recognize additions to the allowance based on their judgments about information available to them at the time of their examination. Because of these factors, it is reasonably possible that the allowance for loan losses may change materially in the near term. However, the amount of the change that is reasonably possible cannot be estimated. Other estimates that are susceptible to significant change in the near term relate to the determination of other-than-temporary impairments of securities and the fair value of financial instruments.
Reclassifications	Reclassifications Certain reclassifications have been made to the 2015 financial statements to be consistent with the 2016 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 have 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 326 “Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments” Update No. 2016-13. The Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) No. 2016-13 in June 2016. The revised accounting guidance requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts and requires enhanced disclosures related to the significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an organization’s portfolio. In addition, ASU 2016-13 amends the accounting for credit losses of available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 will be effective on January 1, 2020. Management is currently evaluating the potential impact of ASU 2016-13 on the consolidated financial statements.