Condensed Parent Company Only Financial Statements - Condensed Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Parent Company Only Financial Information [Line Items]
Cash in bank	$ 251,994us-gaap_CashAndDueFromBanks	$ 238,672us-gaap_CashAndDueFromBanks
Other assets	589,400us-gaap_OtherAssets	554,167us-gaap_OtherAssets
Total Assets	15,758,605us-gaap_Assets	13,365,550us-gaap_Assets	13,129,678us-gaap_Assets
Liabilities	13,905,756us-gaap_Liabilities	11,834,571us-gaap_Liabilities
Shareholders' Equity	1,852,849us-gaap_StockholdersEquity	1,530,979us-gaap_StockholdersEquity	1,529,868us-gaap_StockholdersEquity	1,482,661us-gaap_StockholdersEquity
Total liabilities and shareholders' equity	15,758,605	13,365,550
IBERIABANK Corporation [Member]
Parent Company Only Financial Information [Line Items]
Cash in bank	36,064	98,108
Investment in subsidiaries	1,842,120	1,487,337
Other assets	119,494	80,528
Total Assets	1,997,678	1,665,973
Liabilities	144,829	134,994
Shareholders' Equity	1,852,849	1,530,979
Total liabilities and shareholders' equity	$ 1,997,678	$ 1,665,973

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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Amount of liabilities and equity items, including the portion of equity attributable to noncontrolling interests, if any.

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The aggregate carrying amounts, as of the balance sheet date, of assets not separately disclosed in the balance sheet.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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