Mortgage Banking - Changes in the Reserve for Mortgage Loan Servicing Putback Expense (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of changes in the reserve for mortgage loan [Abstract]
Balance at beginning of period		$ 1,130	$ 1,685	$ 1,170
Provision for putback expenses		(836)	420	315
Other	[1]	706	(975)	200
Balance at end of period		$ 1,000	$ 1,130	$ 1,685

[1] Includes fair value adjustments for loans transferred due to underwriting issues as well as adjustments based on Trustmark’s mortgage loan servicing putback reserve analysis.