Commitments and Contingencies - Summary of Changes in ACL on Off-balance Sheet Credit Exposures (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period		$ 35,623	$ 38,572	$ 0
FASB ASU 2016-13 adoption adjustment		0	0	29,638
PCL, off-balance sheet credit exposures	[1]	1,215	(2,949)	8,934
Balance at end of period		$ 36,838	$ 35,623	$ 38,572

[1] During 2021, Trustmark reclassified its credit loss expense on off-balance sheet credit exposures from noninterest expense to PCL, off-balance sheet credit exposures. Prior periods have been reclassified accordingly.