Stockholders' Equity (Compliance with Regulatory Capital Requirements) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Tier 1 leverage capital, Actual, Amount	$ 2,391,762	$ 2,214,723
Common equity tier 1 (to risk weighted assets), Actual, Amount	2,391,762	2,214,723
Tier 1 capital (to risk weighted assets), Actual, Amount	2,391,762	2,214,723
Total capital (to risk weighted assets), Actual, Amount	$ 2,736,276	$ 2,582,031
Tier 1 leverage capital, Actual, Ratio %	8.67%	8.43%
Common equity tier 1 (to risk weighted assets), Actual, Ratio %	10.48%	10.21%
Tier 1 capital (to risk weighted assets), Actual, Ratio %	10.48%	10.21%
Total capital (to risk weighted assets), Actual, Ratio %	11.99%	11.90%
Tier 1 leverage capital, Required for Minimum Capital Adequacy, Amount	$ 1,103,544	$ 1,051,025
Common equity tier 1 (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	1,026,637	976,303
Tier 1 capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	1,368,849	1,301,738
Total capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	$ 1,825,132	$ 1,735,650
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	$ 1,379,430	$ 1,313,781
Common equity tier 1 (to risk weighted assets), Required To Be Well Capitalized, Amount	1,482,920	1,410,216
Tier 1 capital (to risk weighted assets), Required To Be Well Capitalized, Amount	1,825,132	1,735,650
Total capital (to risk weighted assets), Required To Be Well Capitalized, Amount	$ 2,281,415	$ 2,169,563
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%
Hancock Whitney Bank [Member]
Tier 1 leverage capital, Actual, Amount	$ 2,351,090	$ 2,282,485
Common equity tier 1 (to risk weighted assets), Actual, Amount	2,351,090	2,282,485
Tier 1 capital (to risk weighted assets), Actual, Amount	2,351,090	2,282,485
Total capital (to risk weighted assets), Actual, Amount	$ 2,545,604	$ 2,499,793
Tier 1 leverage capital, Actual, Ratio %	8.54%	8.72%
Common equity tier 1 (to risk weighted assets), Actual, Ratio %	10.32%	10.54%
Tier 1 capital (to risk weighted assets), Actual, Ratio %	10.32%	10.54%
Total capital (to risk weighted assets), Actual, Ratio %	11.17%	11.55%
Tier 1 leverage capital, Required for Minimum Capital Adequacy, Amount	$ 1,101,372	$ 1,046,644
Common equity tier 1 (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	1,025,355	974,362
Tier 1 capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	1,367,140	1,299,150
Total capital (to risk weighted assets), Required for Minimum Capital Adequacy, Amount	$ 1,822,053	$ 1,732,200
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	$ 1,376,715	$ 1,308,305
Common equity tier 1 (to risk weighted assets), Required To Be Well Capitalized, Amount	1,481,068	1,407,412
Tier 1 capital (to risk weighted assets), Required To Be Well Capitalized, Amount	1,822,853	1,732,200
Total capital (to risk weighted assets), Required To Be Well Capitalized, Amount	$ 2,278,566	$ 2,165,250
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%