Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Feb. 24, 2020	Jun. 30, 2019
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-37532
Entity Registrant Name	IBERIABANK Corp
Entity Incorporation, State or Country Code	LA
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
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 4.0
Entity Common Stock, Shares Outstanding		52,583,117
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0000933141
Current Fiscal Year End Date	--12-31
Common Stock
Entity Information [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 Information [Line Items]
Title of 12(b) Security	a Share of 6.625% Perpetual Preferred Stock, Series B
Trading Symbol	IBKCP
Security Exchange Name	NASDAQ
Series C Preferred Stock
Entity Information [Line Items]
Title of 12(b) Security	a Share of 6.60% Perpetual Preferred Stock, Series C
Trading Symbol	IBKCO
Security Exchange Name	NASDAQ
Series D Preferred Stock
Entity Information [Line Items]
Title of 12(b) Security	a Share of 6.100% Perpetual Preferred Stock, Series D
Trading Symbol	IBKCN
Security Exchange Name	NASDAQ