Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2015
Accounting Policies [Abstract]
General	General The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all information or footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal and recurring items, necessary for a fair presentation of the consolidated financial statements have been made. These interim financial statements should be read in conjunction with the audited consolidated financial statements and footnote disclosures for IBERIABANK Corporation (the “Company”) previously filed with the Securities and Exchange Commission (the “SEC”) in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Operating results for the three and nine month periods ended September 30, 2015 are not necessarily indicative of the results that may be expected for the year ended December 31, 2015. The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, IBERIABANK, Lenders Title Company (“LTC”), IBERIA Capital Partners, LLC (“ICP”), 1887 Leasing, LLC, IBERIA Asset Management, Inc. (“IAM”), and IBERIA CDE, LLC (“CDE”). All significant intercompany balances and transactions have been eliminated in consolidation. The Company offers commercial and retail banking products and services to customers throughout locations in seven states through IBERIABANK. The Company also operates mortgage production offices in 10 states through IBERIABANK Mortgage Company (“IMC”), a subsidiary of IBERIABANK, and offers a full line of title insurance and closing services throughout Arkansas and Louisiana through LTC and its subsidiaries. ICP provides equity research, institutional sales and trading, and corporate finance services. 1887 Leasing, LLC owns an aircraft used by management of the Company. IAM provides wealth management and trust services for commercial and private banking clients. CDE is engaged in the purchase of tax credits.
Reclassifications	Reclassifications Certain amounts reported in prior periods have been reclassified to conform to the current period presentation. These reclassifications did not have a material effect on previously reported consolidated net income, shareholders’ equity or cash flows.
Louisiana Business Corporation Act	Louisiana Business Corporation Act Effective January 1, 2015, companies incorporated under Louisiana law became subject to the Louisiana Business Corporation Act (which replaced the Louisiana Business Corporation Law). Provisions of the Louisiana Business Corporation Act eliminate the concept of treasury stock and provide that shares reacquired by a company are to be treated as authorized but unissued shares. As a result of this change in law, shares previously classified as treasury stock are presented as a reduction to issued shares of common stock in the consolidated financial statements as of September 30, 2015, reducing the stated value of common stock and additional paid-in capital.
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 amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Material estimates that are susceptible to significant change in the near term are the allowance for credit losses, accounting for loans covered by loss sharing arrangements with the FDIC and the related loss share receivables, and determination of the fair value of net assets acquired in acquisitions.
Concentration of Credit Risks	Concentrations of Credit Risk Most of the Company’s business activity is with customers located within the states of Louisiana, Florida, Arkansas, Alabama, Texas, Tennessee and Georgia. The Company’s lending activity is concentrated in its market areas in those states. The Company has emphasized originations of commercial loans and private banking loans, defined as loans to larger consumer clients. Repayments on loans are expected to come from cash flows of the borrower and/or guarantor. Losses on secured loans are limited by the value of the collateral upon default of the borrowers. The Company does not have any significant concentrations to any one industry or customer.
Recent Accounting Pronouncements	ASU No. 2014-01 In January 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-01, “Investments – Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects (a consensus of the FASB Emerging Issues Task Force)”. The ASU allows for use of the proportional amortization method for investments in qualified affordable housing projects if certain conditions are met. Under the proportional amortization method, the initial cost of the investment is amortized in proportion to the tax credits and other tax benefits received and the net investment performance is recognized in the consolidated statements of comprehensive income as a component of income tax expense. ASU 2014-01 provides for a practical expedient, which allows for amortization of the investment in proportion to only the tax credits if it produces a measurement that is substantially similar to the measurement that would result from using both tax credits and other tax benefits. ASU 2014-01 was effective for fiscal years and interim periods beginning after December 15, 2014. The Company adopted this guidance effective January 1, 2015, utilizing the practical expedient method. Amortization expense related to qualified affordable housing investments has been presented net of the income tax credits in income tax expense in the unaudited consolidated statements of comprehensive income. The standard was required to be applied retrospectively, therefore, prior periods have been restated in accordance with GAAP. The impact of the adoption of ASU 2014-01 was not material to the consolidated financial statements in current or prior periods. ASU No. 2015-02 In February 2015, the FASB issued ASU No. 2015-02, Consolidation: Amendments to the Consolidation Analysis, which changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. The amendments in the guidance: 1) modify the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities, 2) eliminate the presumption that a general partner should consolidate a limited partnership, 3) affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships, and 4) provide a scope exception from consolidation guidance for certain investment funds. ASU No. 2015-02 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The guidance may be applied using a modified retrospective approach by recording a cumulative effect adjustment to equity as of the beginning of the fiscal year of adoption. The amendments may also be applied retrospectively. The Company is still evaluating this ASU but does not expect that adoption will have a significant impact on the Company’s consolidated financial statements. ASU No. 2015-16 In September 2015, the FASB issued ASU No. 2015-16, Business Combinations: Simplifying the Accounting for Measurement-Period Adjustments. ASU No. 2015-16 requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined and present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been have been recorded in previous reporting periods if the adjustment had been recognized as of the acquisition date. ASU No. 2015-16 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The guidance must be applied prospectively to adjustments to provisional amounts that occur after the effective date of this update with earlier application permitted for financial statements that have not been issued. The Company adopted this guidance effective September 30, 2015. The adoption of this ASU did not have a significant impact on the Company’s consolidated financial statements.