Borrowed Funds - Summary of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt issue cost and unamortized premium	$ (1,137)	$ (1,211)
Purchased	(10,078)	(10,078)
Total long-term debt	283,785	283,711
Cadence Bancorporation
Debt Instrument [Line Items]
Long-term debt, gross	270,000	270,000
Cadence Bancorporation | 4.875% Senior Notes, Due June 28, 2019
Debt Instrument [Line Items]
Long-term debt, gross	145,000	145,000
Cadence Bancorporation | 5.375% Senior Notes, Due June 28, 2021
Debt Instrument [Line Items]
Long-term debt, gross	50,000	50,000
Cadence Bancorporation | 7.250% Subordinated Notes, Due June 28, 2029, Callable in 2024
Debt Instrument [Line Items]
Long-term debt, gross	35,000	35,000
Cadence Bancorporation | 6.500% Subordinated Notes, Due March 2025, Callable in 2020
Debt Instrument [Line Items]
Long-term debt, gross	40,000	40,000
Cadence Bank | 6.250% Subordinated Notes, Due June 28, 2029, Callable in 2024
Debt Instrument [Line Items]
Long-term debt, gross	$ 25,000	$ 25,000