Capital Requirements And Other Regulatory Matters (Actual Capital Amounts And Ratios) (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010
IBERIABANK Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage capital, Actual Amount	$ 1,164,801	$ 1,132,777
Tier 1 leverage capital, Minimum Amount	445,905	403,057
Tier 1 risk-based capital, Actual Amount	1,164,801	1,132,777
Tier 1 risk-based capital, Minimum Amount	311,908	245,236
Total risk-based capital, Actual Amount	1,263,496	1,210,180
Total risk-based capital, Minimum Amount	623,816	490,472
Tier 1 leverage capital, Actual Ratio	10.45%	11.24%
Tier 1 leverage capital, Minimum Ratio	4.00%	4.00%
Tier 1 risk-based capital, Actual Ratio	14.94%	18.48%
Tier 1 risk-based capital, Minimum Ratio	4.00%	4.00%
Total risk-based capital, Actual Ratio	16.20%	19.74%
Total risk-based capital, Minimum Ratio	8.00%	8.00%
IBERIABANK [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage capital, Actual Amount	997,277	690,771
Tier 1 leverage capital, Minimum Amount	443,165	339,330
Tier 1 leverage capital, Well Capitalized Amount	553,956	424,162
Tier 1 risk-based capital, Actual Amount	997,277	690,771
Tier 1 risk-based capital, Minimum Amount	309,802	192,025
Tier 1 risk-based capital, Well Capitalized Amount	464,703	288,037
Total risk-based capital, Actual Amount	1,095,322	751,481
Total risk-based capital, Minimum Amount	619,604	384,049
Total risk-based capital, Well Capitalized Amount	$ 774,505	$ 480,062
Tier 1 leverage capital, Actual Ratio	9.00%	8.14%
Tier 1 leverage capital, Minimum Ratio	4.00%	4.00%
Tier 1 leverage capital, Well Capitalized Ratio	5.00%	5.00%
Tier 1 risk-based capital, Actual Ratio	12.88%	14.39%
Tier 1 risk-based capital, Minimum Ratio	4.00%	4.00%
Tier 1 risk-based capital, Well Capitalized Ratio	6.00%	6.00%
Total risk-based capital, Actual Ratio	14.14%	15.65%
Total risk-based capital, Minimum Ratio	8.00%	8.00%
Total risk-based capital, Well Capitalized Ratio	10.00%	10.00%