Condensed Financial Information of Cadence Bancorporation (Parent Only) - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INCOME
Interest income	$ 143,857	$ 131,753	$ 123,963	$ 113,093	$ 108,370	$ 99,503	$ 99,375	$ 89,619	$ 512,666	$ 396,867	$ 335,250
Other income									18,111	24,656	17,678
EXPENSES
Interest expense	40,711	33,653	28,579	21,982	20,459	18,340	16,991	14,861	124,925	70,651	55,811
Other expenses									67,180	60,665	60,598
Income before income taxes	43,035	62,210	56,358	49,775	51,671	50,034	42,538	38,756	211,378	182,999	98,314
Income tax expense (benefit)	10,709	15,074	8,384	10,950	36,980	17,457	13,570	12,639	45,117	80,646	32,540
Net income	$ 32,326	$ 47,136	$ 47,974	$ 38,825	$ 14,691	$ 32,577	$ 28,968	$ 26,117	166,261	102,353	65,774
Cadence Bancorporation
INCOME
Dividends from bank subsidiary									59,494	11,000	13,500
Interest income									73	65	25
Other income									516	632	176
Total income									60,083	11,697	13,701
EXPENSES
Interest expense									17,626	17,424	18,060
Other expenses									7,048	3,305	2,092
Total expenses									24,674	20,729	20,152
Income (loss) before income taxes and equity in undistributed income of subsidiaries									35,409	(9,032)	(6,451)
Equity in undistributed income of subsidiaries									125,727	103,390	64,424
Income before income taxes									161,136	94,358	57,973
Income tax expense (benefit)									(5,125)	(7,995)	(7,801)
Net income									$ 166,261	$ 102,353	$ 65,774