Condensed Parent Company Only Financial Statements (Condensed Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Cash in bank	$ 194,171	$ 94,941
Other assets	592,112	507,497
Total assets	11,757,928	10,026,766
Liabilities	10,275,267	8,723,309
Shareholders' equity	1,482,661	1,303,457	961,318	734,208
Total liabilities and shareholders' equity	11,757,928	10,026,766
IBERIABANK Corporation [Member]
Cash in bank	98,390	234,006
Investment in subsidiaries	1,434,101	1,123,168
Other assets	75,061	49,980
Total assets	1,607,552	1,407,154
Liabilities	124,891	103,697
Shareholders' equity	1,482,661	1,303,457
Total liabilities and shareholders' equity	$ 1,607,552	$ 1,407,154