Earnings Per Share (Schedule Showing Calculation Of Basic And Diluted Earnings Per Share) (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
Earnings Per Share, Basic And Diluted, By Common Class, Including Two Class Method [Line Items]
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
Distributed and undistributed earnings to unvested restricted stock									(988,000)		(981,000)		(4,217,000)
Distributed and undistributed earnings to common shareholders - Basic									52,550,000	[1]	47,845,000	[1]	150,787,000	[1]
Undistributed earnings reallocated to unvested restricted stock									21,000		10,000		307,000
Distributed and undistributed earnings to common shareholders - Diluted									52,571,000		47,855,000		151,094,000
Weighted average shares outstanding- Basic									28,500,420	[2]	25,681,266	[2]	18,210,867	[2]
Weighted average shares outstanding- Diluted									28,141,300		25,394,120		17,956,674
Earnings per common share - Basic	$ 0.59	$ 0.55	$ 0.19	$ 0.54	$ 0.49	$ 0.52	$ 0.33	$ 0.60	$ 1.88	[1]	$ 1.90	[1]	$ 8.49	[1]
Earnings per common share - Diluted	$ 0.59	$ 0.54	$ 0.18	$ 0.54	$ 0.48	$ 0.52	$ 0.33	$ 0.59	$ 1.87		$ 1.88		$ 8.41
Distributed earnings									38,681,000		35,772,000		24,491,000
Distributed earnings, per weighted average share									$ 1.38		$ 1.42		$ 1.38
Undistributed earnings									13,869,000		12,073,000		126,296,000
Undistributed earnings, per weighted average share									$ 0.50		$ 0.48		$ 7.11
Weighted average basic shares outstanding, unvested restricted stock									484,361		498,692		457,213
Unvested Restricted Stock [Member]
Earnings Per Share, Basic And Diluted, By Common Class, Including Two Class Method [Line Items]
Earnings per common share - Basic									$ 2.04	[3]	$ 1.97	[3]	$ 9.22	[3]
Earnings per common share - Diluted									$ 2.00		$ 1.95		$ 8.55
Distributed earnings									727,000		733,000		685,000
Distributed earnings, per weighted average share									$ 1.50		$ 1.47		$ 1.50
Undistributed earnings									261,000		248,000		3,532,000
Undistributed earnings, per weighted average share									$ 0.54		$ 0.50		$ 7.73
IBERIABANK Corporation [Member]
Earnings Per Share, Basic And Diluted, By Common Class, Including Two Class Method [Line Items]
Income available to common shareholders									$ 53,538,000		$ 48,826,000		$ 155,004,000

[1] Total earnings available to common shareholders include distributed earnings of $38,681,000, or $1.38 per weighted average share, and undistributed earnings of $13,869,000, or $0.50 per weighted average share for the year ended December 31, 2011. Total earnings available to common shareholders include distributed earnings of $35,772,000, or $1.42 per weighted average share, and undistributed earnings of $12,073,000, or $0.48 per weighted average share for the year ended December 31, 2010. Total earnings available to common shareholders include distributed earnings of $24,491,000, or $1.38 per weighted average share, and undistributed earnings of $126,296,000, or $7.11 per weighted average share for the year ended December 31, 2009.

[2] Weighted average basic shares outstanding include 484,361, 498,692, and 457,213 shares of unvested restricted stock for the years ended December 31, 2011, 2010, and 2009, respectively.

[3] Total earnings available to unvested restricted stock include distributed earnings of $727,000, or $1.50 per weighted average share, and undistributed earnings of $261,000, or $0.54 per weighted average share for the year ended December 31, 2011. Total earnings available to unvested restricted stock include distributed earnings of $733,000, or $1.47 per weighted average share, and undistributed earnings of $248,000, or $0.50 per weighted average share for the year ended December 31, 2010. Total earnings available to unvested restricted stock include distributed earnings of $685,000, or $1.50 per weighted average share, and undistributed earnings of $3,532,000, or $7.73 per weighted average share, under the two-class method for the year ended December 31, 2009.