Premises and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Premises and Equipment, Net, by Type [Abstract]
Depreciation and amortization of premises and equipment	$ 14.0	$ 14.1	$ 14.3

The aggregate amount of depreciation, amortization of premises and equipment recognized during the accounting period.

No definition available.

Name:	trmk_DepreciationAndAmortizationOfPremisesAndEquipment
Namespace Prefix:	trmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration