Business, Basis of Financial Statement Presentation and Principles of Consolidation (Details)	3 Months Ended
Mar. 31, 2012
Business, Basis of Financial Statement Presentation and Principles of Consolidation [Abstract]
Number of offices in Florida, Mississippi, Tennessee and Texas	approximately 170

Number of office locations within a specified geographic area, state or grouping of named states.

No definition available.

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Namespace Prefix:	trmk_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration