Condensed Parent Company Only Financial Statements (Condensed Statements Of Income) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other income									$ 15,782,000	$ 15,683,000	$ 7,647,000
Interest expense	19,226,000	20,995,000	21,162,000	20,686,000	25,367,000	29,885,000	31,078,000	28,414,000	82,069,000	114,744,000	97,602,000
Salaries and employee benefits expense									193,773,000	161,482,000	114,379,000
Other expenses									66,816,000	56,753,000	39,069,000
Income (loss) before income tax (expense) benefit and increase in equity in undistributed earnings of subsidiaries	24,024,000	22,398,000	4,257,000	19,840,000	18,075,000	21,215,000	12,169,000	17,358,000	70,519,000	68,817,000	248,692,000
Income tax benefit	6,667,000	6,051,000	(929,000)	5,193,000	5,033,000	7,275,000	3,329,000	4,354,000	16,981,000	19,991,000	90,338,000
Net income	17,357,000	16,347,000	5,186,000	14,647,000	13,042,000	13,940,000	8,840,000	13,004,000	53,538,000	48,826,000	158,354,000
Preferred Stock Dividends											(3,350,000)
Income available to common shareholders	17,357,000	16,347,000	5,186,000	14,647,000	13,042,000	13,940,000	8,840,000	13,004,000	53,538,000	48,826,000	155,004,000
IBERIABANK Corporation [Member]
Dividends from subsidiaries
Reimbursement of management expenses									74,664,000	41,313,000	34,280,000
Other income									(1,176,000)	1,209,000	1,544,000
Total operating income									73,488,000	42,522,000	35,824,000
Interest expense									2,101,000	3,865,000	4,464,000
Salaries and employee benefits expense									63,505,000	49,816,000	35,719,000
Other expenses									33,546,000	24,744,000	16,241,000
Total operating expenses									99,152,000	78,425,000	56,424,000
Income (loss) before income tax (expense) benefit and increase in equity in undistributed earnings of subsidiaries									(25,664,000)	(35,903,000)	(20,600,000)
Income tax benefit									8,219,000	12,113,000	7,108,000
Income (loss) before equity in undistributed earnings of subsidiaries									(17,445,000)	(23,790,000)	(13,492,000)
Equity in undistributed earnings of subsidiaries									70,983,000	72,616,000	171,845,000
Net income									53,538,000	48,826,000	158,354,000
Preferred Stock Dividends											(3,350,000)
Income available to common shareholders									$ 53,538,000	$ 48,826,000	$ 155,004,000