Acquired Loans - Carrying Amount of Acquired Loans by Credit Quality Indicator (Parenthetical) (Details)	Mar. 31, 2016	Dec. 31, 2015
Certain Loans Acquired In Transfer Not Accounted For As Debt Securities [Abstract]
Percentage of risk of losses incurred on acquired covered loans	20.00%	20.00%

The percentage of risk of losses incurred on acquired covered loans.

No definition available.

Name:	trmk_PercentageOfRiskOfLossesIncurredOnAcquiredLoans
Namespace Prefix:	trmk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant