Retirement and Employee Benefit Plans (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Number of consecutive year level of compensation for non qualified benefit pension plan	5 years
Number of final years of employment for non qualified benefit pension plan	10 years
Minimum service period must have completed to become vested in the Company's contributions	3 Years
Time period completed by employee to cover under defined benefit pension plan	1 year
Plan assets	$ 224,585,000
Number of shares of parent company included in plan assets	16,375
Value of Shares of Parent Company Included in Plan Assets	500,000
Percentage of shares of parent company included in plan assets	0.23%
Period of employment required to cover employee stock purchase plan	90 days
Hancock [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit increase (decrease) in pre- and post-medicare age health costs plan year in which rate reaches ultimate trend rate	5 years	6 years
Defined Benefit Plan-Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum number of hours worked by employee to cover under defined benefit pension plan	1,000 hours
Anticipated contributions	22,200,000
Cash equivalents	25,000,000
Defined Benefit Plan-Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.25%
Defined Contribution Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of savings for calculating each employee participation in plan	50.00%
Maximum percentage of compensation on base percentage for participating in plan	6.00%
Period of employment required to cover employee under retirement plan	90 days
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Age of employee at retirement to cover under defined benefit postretirement plan	65 years
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Age of employee at retirement to cover under defined benefit postretirement plan	55 years
S&P 500 Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Return on investment	55.00%
Barclays Intermediate Aggregate Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Return on investment	45.00%
Hancock Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	109,100,000	83,600,000
Net actuarial loss included in accumulated other comprehensive income	4,600,000
Discount rate		5.30%
Plan assets	103,475,000	71,640,000
Contributions	4,500,000	2,000,000	1,800,000
Increase (decrease) in pre- and post-medicare age health costs rate	7.50%	8.00%
Decrease in ultimate rate over a period of time	5.00%	5.00%
Year of service who have reached 55 years of age	10 years
Year of service who have reached 65 years of age	5 years
Minimum age for increase in per capita cost of health care benefit	65 years
Period over assumed percentage to decrease for health care benefits	5 years	6 years
Hancock Plan [Member] | Defined Benefit Plan-Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Project benefit obligation	135,115,000	101,746,000	89,720,000
Discount rate	4.35%	5.46%	5.95%
Plan assets	103,475,000	71,640,000	61,313,000
Contributions	34,907,000	6,726,000
Hancock Plan [Member] | Defined Benefit Plan-Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Project benefit obligation	16,653,000	12,373,000	10,290,000
Plan assets	0	0	0
Contributions	763,000	696,000
Whitney Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss included in accumulated other comprehensive income	3,000,000
Maximum percentage of compensation on base percentage for participating in plan	4.00%
Discount rate	4.10%
Discretionary profit-sharing contribution by employer	1,300,000
Maximum percentage of plan assets to hold debt securities	10.00%
Maximum percentage of plan market value to equity securities	5.00%
Increase (decrease) in pre- and post-medicare age health costs rate	7.75%
Decrease in ultimate rate over a period of time	5.00%
Maximum average life of all purchases for debt portfolio	10 years
Minimum age for increase in per capita cost of health care benefit	65 years
Period over assumed percentage to decrease for health care benefits	8 years
Period over assumed percentage to decrease for health care benefits to decrease further	5 years
Whitney Plan [Member] | Defined Benefit Plan-Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Project benefit obligation	17,454,000	15,949,000
Plan assets	0	0
Contributions	620,000
Qualified [Member] | Whitney Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	239,100,000
Qualified [Member] | Whitney Plan [Member] | Defined Benefit Plan-Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Project benefit obligation	264,393,000	216,992,000
Discount rate	4.31%
Plan assets	224,585,000	223,495,000
Contributions	10,000,000
Nonqualified [Member] | Whitney Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	15,700,000
Nonqualified [Member] | Whitney Plan [Member] | Defined Benefit Plan-Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Project benefit obligation	15,934,000	14,442,000
Discount rate	4.31%
Plan assets	0	0
Contributions	$ 570,000