Share-Based Payment Arrangements (Schedule Of Option Activity Under Stock Option Plans) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2011
Share-Based Payment Arrangements
Number of Shares, Outstanding at Beginning Balance	1,129,520
Number of Shares, Whitney Bank options at acquisition date	775,261
Number of Shares, Granted
Number of Shares, Exercised	(5,194)
Number of Shares, Forfeited or expired	(66,400)
Number of Shares, Outstanding at Ending Balance	1,833,187
Number of Shares, Exercisable at Ending Balance	1,415,195
Number of Shares, Share options expected to vest	417,992
Weighted- Average Exercise Price, Outstanding at Beginning Balance	$ 35.08
Weighted- Average Exercise Price, Whitney Bank options at acquisition date	$ 62.64
Weighted- Average Exercise Price, Granted
Weighted- Average Exercise Price, Exercised	$ 22.07
Weighted- Average Exercise Price, Forfeited or expired	$ 43.78
Weighted- Average Exercise Price, Outstanding at Ending Balance	$ 46.45
Weighted- Average Exercise Price, Exercisable at Ending Balance	$ 49.48
Weighted- Average Exercise Price, Share options expected to vest	$ 36.19
Weighted-Average Remaining Contractual Term, Outstanding at Beginning Balance	6.3
Weighted-Average Remaining Contractual Term, Whitney Bank options at acquisition date	1.8
Weighted-Average Remaining Contractual Term, Outstanding at Ending Balance	3.5
Weighted-Average Remaining Contractual Term, Exercisable at Ending Balance	2.9
Weighted-Average Remaining Contractual Term, Share options expected to vest	8.5
Aggregate Intrinsic Value, Outstanding at Ending Balance	$ 1,197
Aggregate Intrinsic Value, Exercisable at Ending Balance	$ 1,197