| Cover Page | Apr. 17, 2020 |
| Entity Listings [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Apr. 17, 2020 |
| Entity Registrant Name | IBERIABANK CORP |
| Entity Incorporation, State or Country Code | LA |
| Entity File Number | 001-37532 |
| Entity Tax Identification Number | 72-1280718 |
| Entity Address, Address Line One | 200 West Congress Street |
| Entity Address, City or Town | Lafayette |
| Entity Address, State or Province | LA |
| Entity Address, Postal Zip Code | 70501 |
| City Area Code | 337 |
| Local Phone Number | 521-4003 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000933141 |
| Common Stock | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Common Stock (par value $1.00 per share) |
| Trading Symbol | IBKC |
| Security Exchange Name | NASDAQ |
| Series B Preferred Stock | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Depositary Shares, Each Representing a 1/400th Interest in |
| Trading Symbol | IBKCP |
| Security Exchange Name | NASDAQ |
| Series C Preferred Stock | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Depositary Shares, Each Representing a 1/400th Interest in |
| Trading Symbol | IBKCO |
| Security Exchange Name | NASDAQ |
| Series D Preferred Stock | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Depositary Shares, Each Representing a 1/400th Interest in |
| Trading Symbol | IBKCN |
| Security Exchange Name | NASDAQ |
