Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Loss Contingencies [Line Items]
Rental expense	$ 7,500,000	$ 6,500,000	$ 6,400,000
Future minimum rental commtiments under noncancellable operating leases [Abstract]
2012	5,913,000
2013	4,985,000
2014	3,876,000
2015	3,097,000
2016	1,122,000
Thereafter	5,718,000
Total	24,711,000
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Maximum potential exposure to credit loss in the event of nonperformance	156,700,000	185,600,000
Letters of Credit, Maturity Term - Maximum (in years)	3 Y
Collateral Held, Fair Value	52,800,000
Trustmark National Bank [Member] | Pending or Threatened Litigation [Member]
Legal Proceedings [Abstract]
Lawsuits Naming Entity as Defendant, number	2
Commitments to Extend Credit [Member]
Commitments for credit [Abstract]
Commitments to extend credit	$ 1,700,000,000	$ 1,600,000,000