Basis of Presentation - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Basis Of Presentation [Line Items]
Company mortgage loans held for sale	$ 188,037,000
Property write-downs	$ 1,154,000	$ 2,556,000
Commercial [Member]
Basis Of Presentation [Line Items]
Loss sharing indemnification agreements, term	5 years
Single family residential [Member]
Basis Of Presentation [Line Items]
Loss sharing indemnification agreements, term	10 years
IBERIABANK Corporation [Member]
Basis Of Presentation [Line Items]
Number of operating states	6
IBERIABANK Mortgage Company [Member]
Basis Of Presentation [Line Items]
Number of operating states	12