Acquired Loans - Changes in the Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		$ 105,701
Accretion to interest income		5,532	$ 9,514		$ 14,924
Carrying value, net, ending		71,786	105,701
Acquired Not ASC 310-30 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	2,811	77,868
Transfers	[1],[2]	(2,926)	(59,916)	[3]
Accretion to interest income	[1]	115	1,019
Payments received, net	[1]	0	(16,234)
Other	[1],[4]	0	74
Change in allowance for loan losses, acquired loans	[1]	0	0
Carrying value, net, ending	[1]	0	2,811		77,868
Acquired Impaired [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		102,890	179,570
Transfers	[2]	0	(26,497)	[3]
Accretion to interest income		5,532	9,514
Payments received, net		(37,230)	(62,519)
Other	[4]	178	(26)
Change in allowance for loan losses, acquired loans		416	2,848
Carrying value, net, ending		$ 71,786	$ 102,890		$ 179,570

[1] “Acquired Not ASC 310-30” loans consist of loans that are not in scope for FASB ASC Subtopic 310-30.

[2] “Acquired Not ASC 310-30” loans transferred to LHFI due to the discount on these loans being fully amortized.

[3] During 2018, Trustmark transferred the remaining loans acquired in the Bay Bank, Heritage and Reliance acquisitions from acquired impaired loans to LHFI.

[4] Includes miscellaneous timing adjustments as well as acquired loan terminations through foreclosure, charge-off and other terminations.