Stockholders' Equity (Compliance with Regulatory Capital Requirements) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Hancock Holding Company [Member]
Tier 1 leverage capital, Actual, Amount	$ 2,214,723	$ 2,184,812
Common equity tier 1 (to risk weighted assets), Actual, Amount	2,214,723	2,184,812
Tier 1 capital (to risk weighted assets), Actual, Amount	2,214,723	2,184,812
Total capital (to risk weighted assets), Actual, Amount	$ 2,582,031	$ 2,564,230
Tier 1 leverage capital, Actual, Ratio %	8.43%	9.56%
Common equity tier 1 (to risk weighted assets), Actual, Ratio %	10.21%	11.26%
Tier 1 capital (to risk weighted assets), Actual, Ratio %	10.21%	11.26%
Total capital (to risk weighted assets), Actual, Ratio %	11.90%	13.21%
Tier 1 leverage capital, Required for Minimum Capital Adequacy, Amount	$ 1,051,025	$ 914,520
Common equity tier 1 (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	976,303	873,192
Tier 1 capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	1,301,738	1,164,256
Total capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	$ 1,735,650	$ 1,552,341
Tier 1 leverage capital, Required for Minimum Capital Adequacy, Ratio %	4.00%	4.00%
Common equity tier 1 (to risk weighted assets), Required for Minimum Capital Adequacy, Ratio %	4.50%	4.50%
Tier 1 capital (to risk weighted assets), Required for Minimum Capital Adequacy, Ratio %	6.00%	6.00%
Total capital (to risk weighted assets), Required for Minimum Capital Adequacy, Ratio %	8.00%	8.00%
Tier 1 leverage capital, Required To Be Well Capitalized, Amount	$ 1,313,781	$ 1,143,150
Common equity tier 1 (to risk weighted assets), Required To Be Well Capitalized, Amount	1,410,216	1,261,277
Tier 1 capital (to risk weighted assets), Required To Be Well Capitalized, Amount	1,735,650	1,552,341
Total capital (to risk weighted assets), Required To Be Well Capitalized, Amount	$ 2,169,563	$ 1,940,427
Tier 1 leverage capital, Required To Be Well Capitalized, Ratio %	5.00%	5.00%
Common equity tier 1 (to risk weighted assets), Required To Be Well Capitalized, Ratio %	6.50%	6.50%
Tier 1 capital (to risk weighted assets), Required To Be Well Capitalized, Ratio %	8.00%	8.00%
Total capital (to risk weighted assets), Required To Be Well Capitalized, Ratio %	10.00%	10.00%
Whitney Bank [Member]
Tier 1 leverage capital, Actual, Amount	$ 2,282,485	$ 2,011,719
Common equity tier 1 (to risk weighted assets), Actual, Amount	2,282,485	2,011,719
Tier 1 capital (to risk weighted assets), Actual, Amount	2,282,485	2,011,719
Total capital (to risk weighted assets), Actual, Amount	$ 2,499,793	$ 2,241,137
Tier 1 leverage capital, Actual, Ratio %	8.72%	8.83%
Common equity tier 1 (to risk weighted assets), Actual, Ratio %	10.54%	10.39%
Tier 1 capital (to risk weighted assets), Actual, Ratio %	10.54%	10.39%
Total capital (to risk weighted assets), Actual, Ratio %	11.55%	11.57%
Tier 1 leverage capital, Required for Minimum Capital Adequacy, Amount	$ 1,046,644	$ 911,091
Common equity tier 1 (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	974,362	871,361
Tier 1 capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	1,299,150	1,161,815
Total capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	$ 1,732,200	$ 1,549,086
Tier 1 leverage capital, Required for Minimum Capital Adequacy, Ratio %	4.00%	4.00%
Common equity tier 1 (to risk weighted assets), Required for Minimum Capital Adequacy, Ratio %	4.50%	4.50%
Tier 1 capital (to risk weighted assets), Required for Minimum Capital Adequacy, Ratio %	6.00%	6.00%
Total capital (to risk weighted assets), Required for Minimum Capital Adequacy, Ratio %	8.00%	8.00%
Tier 1 leverage capital, Required To Be Well Capitalized, Amount	$ 1,308,305	$ 1,138,864
Common equity tier 1 (to risk weighted assets), Required To Be Well Capitalized, Amount	1,407,412	1,258,633
Tier 1 capital (to risk weighted assets), Required To Be Well Capitalized, Amount	1,732,200	1,549,086
Total capital (to risk weighted assets), Required To Be Well Capitalized, Amount	$ 2,165,250	$ 1,936,358
Tier 1 leverage capital, Required To Be Well Capitalized, Ratio %	5.00%	5.00%
Common equity tier 1 (to risk weighted assets), Required To Be Well Capitalized, Ratio %	6.50%	6.50%
Tier 1 capital (to risk weighted assets), Required To Be Well Capitalized, Ratio %	8.00%	8.00%
Total capital (to risk weighted assets), Required To Be Well Capitalized, Ratio %	10.00%	10.00%