Acquired Loans - Changes in the Carrying Value of Acquired Loans (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		$ 260,850
Accretion to interest income		3,673	$ 5,230
Carrying value, net, ending		208,236		$ 260,850
Acquired Not ASC 310-30 [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning	[1]	42,743	67,657	67,657
Accretion to interest income	[1]	0		40
Payments received, net	[1]	(6,024)		(24,953)
Other	[1],[2]	0		0
Less change in allowance for loan losses, acquired loans	[1]	0		(1)
Carrying value, net, ending	[1]	0		42,743
Transfers	[1],[3]	(36,719)
Acquired Impaired [Member]
Carrying value of acquired loans [Abstract]
Carrying value, net, beginning		218,107	$ 310,762	310,762
Accretion to interest income		3,673		18,405
Payments received, net		(14,645)		(111,522)
Other	[2]	(290)		(134)
Less change in allowance for loan losses, acquired loans		1,391		596
Carrying value, net, ending		208,236		$ 218,107
Transfers	[3]	$ 0

[1] "Acquired Not ASC 310-30" loans consist of revolving credit agreements and commercial leases that are not in scope for FASB ASC Topic 310-30, "Loans and Debt Securities Acquired with Deteriorated Credit Quality."

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

[3] During the first quarter of 2017, Trustmark transferred the remaining balance of the “Acquired Not ASC 310-30” loans to LHFI due to the discount on these loans being fully amortized.