Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2016
Accounting Policies [Abstract]
General	General The accompanying unaudited consolidated financial statements have been prepared in accordance with 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 the Company previously filed with the SEC in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. Operating results for the period ended September 30, 2016 are not necessarily indicative of the results that may be expected for the year ending December 31, 2016. When we refer to the “Company,” “we,” “our,” or “us” in this Report, we mean IBERIABANK Corporation and subsidiaries (consolidated). When we refer to the “Parent,” we mean IBERIABANK Corporation. See the Glossary of Acronyms at the end of this Report for terms used throughout this Report.
Principles of Consolidation	Principles of Consolidation The Company’s consolidated financial statements include all entities in which the Company has a controlling financial interest under either the voting interest or variable interest model. The assessment of whether or not the Company has a controlling interest (i.e., the primary beneficiary) in a variable interest entity ("VIE") is performed on an on-going basis. All equity investments in non-consolidated VIEs are included in "other assets" in the Company’s consolidated balance sheets. The Company’s maximum exposure to loss as a result of its involvement with non-consolidated VIEs was approximately $130 million and $160 million at September 30, 2016 and December 31, 2015, respectively. The Company's maximum exposure to loss was equivalent to the carrying value of its investments and any related outstanding loans to the non-consolidated VIEs. Investments in entities that are not consolidated are accounted for under either the equity, cost, or proportional amortization method of accounting. Investments for which the Company has the ability to exercise significant influence over the operating and financing decisions of the entity are accounted for under the equity method. Investments for which the Company does not hold such ability are accounted for under the cost method. Investments in qualified affordable housing projects, which meet certain criteria, are accounted for under the proportional amortization method. The consolidated financial statements include the accounts of the Company and its subsidiaries, IBERIABANK; Lenders Title Company; IBERIA Capital Partners, LLC; 1887 Leasing, LLC; IBERIA Asset Management, Inc.; 840 Denning, LLC; and IBERIA CDE, LLC. All significant intercompany balances and transactions have been eliminated in consolidation.
Nature of Operations	Nature of Operations 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 IMC 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 throughout the energy industry. 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 net impact on previously reported consolidated net income, shareholders’ equity or cash flows.
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, valuation of and accounting for acquired loans, goodwill and other intangibles, income taxes, and fair value estimates.
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. Concentrations in commercial real estate have increased as a result of the Company's recent acquisitions of CRE-focused banks. 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 and guarantor support. The Company does not have any significant concentrations to any one industry or customer.
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS ASU No. 2016-02 In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The most significant amendment to existing GAAP is the recognition of lease assets (i.e., right of use assets) and liabilities on the balance sheet for leases that are classified as operating leases by lessees. The lessor model remains similar to the current accounting model in existing GAAP. Additional amendments include, but are not limited to, the elimination of leveraged leases; modification to the definition of a lease; amendments on sale and leaseback transactions; and disclosure of additional quantitative and qualitative information. ASU 2016-02 will be effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is currently evaluating the impact of the ASU on the Company’s consolidated financial statements, including whether to adopt any practical expedients or policy elections from this ASU. The Company is not expecting to early adopt the ASU. ASU No. 2016-08, No. 2016-10, and No. 2016-12 In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), to improve implementation guidance on principal versus agency considerations within Topic 606. In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, to improve implementation guidance on identifying performance obligations and licensing aspects of Topic 606. In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, to provide clarification on certain targeted aspects of Topic 606. The amendments in ASU No. 2016-08, No. 2016-10, and No. 2016-12 will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that annual reporting period. The amendments will be applied through the election of one of two retrospective methods. The Company is currently evaluating the impact of the ASUs on the Company’s consolidated financial statements. The Company is not expecting to early adopt the ASUs. ASU No. 2016-09 In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The amendments will require recognition of excess tax benefits and deficiencies associated with awards which vest or settle within income tax expense or benefit in the statement of comprehensive income, with the tax effects treated as discrete items in the reporting period in which they occur. The ASU further requires entities to recognize excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. This will eliminate the current APIC pool concept. The amendments will also allow an accounting policy election to account for forfeitures as they occur, permit an entity to withhold up to the maximum statutory tax rates in the applicable jurisdictions while still qualifying for equity classification, and change the classification of certain cash flows associated with stock compensation. ASU 2016-09 will be effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. The transition method for implementing each amendment varies. The Company expects to elect an accounting policy to account for forfeitures as they occur upon adoption. Based on the Company's current stock valuation, it does not anticipate a significant impact to the Company's consolidated financial statements at adoption. ASU No. 2016-13 In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments introduce an impairment model that is based on expected credit losses (“ECL”), rather than incurred losses, to estimate credit losses on certain types of financial instruments (e.g., loans and held-to-maturity securities), including certain off-balance sheet financial instruments (e.g., loan commitments). The ECL should consider historical information, current information, and reasonable and supportable forecasts, including estimates of prepayments, over the contractual term. Financial instruments with similar risk characteristics may be grouped together when estimating the ECL. The ASU also amends the current AFS security impairment model for debt securities. The new model will require an estimate of ECL when the fair value is below the amortized cost of the asset through the use of an allowance to record estimated credit losses (and subsequent recoveries). Non-credit related losses will continue to be recognized through OCI. In addition, the amendments provide for a simplified accounting model for purchased financial assets with a more-than-insignificant amount of credit deterioration since their origination. The initial estimate of expected credit losses would be recognized through an ALL with an offset (i.e., increase) to the cost basis of the related financial asset at acquisition. ASU 2016-13 will be effective for fiscal years beginning after December 15, 2019, including interim periods. The amendments will be applied through a modified-retrospective approach, resulting in a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. A prospective transition approach is required for debt securities for which OTTI had been recognized before the effective date. Amounts previously recognized in AOCI as of the date of adoption that relate to improvements in cash flows expected to be collected should continue to be accreted into income over the remaining life of the asset. Recoveries of amounts previously written off relating to improvements in cash flows after the date of adoption should be recorded in earnings when received. The Company is currently evaluating the impact of the ASU on the Company’s consolidated financial statements. ASU No. 2016-15 In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, in order to reduce current diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. ASU 2016-15 will be effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The amendments should be applied using a retrospective transition method to each period presented. The Company is currently evaluating the impact of the ASU on the Company’s consolidated statement of cash flows.