Retirement and Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in plan assets
Fair value of plan assets, end of year	$ 224,585
Hancock Plan [Member]
Change in plan assets
Fair value of plan assets, beginning of year	71,640
Employer contributions	4,500	2,000	1,800
Fair value of plan assets, end of year	103,475	71,640
Hancock Plan [Member] | Defined Benefit Plan-Pension [Member]
Change in benefit obligation
Benefit obligation, beginning of year	101,746	89,720
Service cost	4,689	3,500	3,107
Service cost defined benefit plans		3,501
Interest cost	5,453	5,233	4,833
Actuarial loss	27,429	7,155
Benefits paid	(4,202)	(3,863)
Benefit obligation, end of year	135,115	101,746	89,720
Change in plan assets
Fair value of plan assets, beginning of year	71,640	61,313
Actual return on plan assets	1,375	7,718
Employer contributions	34,907	6,726
Benefit payments	(4,202)	(3,863)
Expenses	(245)	(254)
Fair value of plan assets, end of year	103,475	71,640	61,313
Funded status at end of year-net liability	(31,640)	(30,106)
Amounts recognized in accumulated other comprehensive loss
Unrecognized loss at beginning of year	38,810	36,753
Amount of (loss)/gain recognized during the year	(2,343)	(2,281)	(2,648)
Net actuarial loss/(gain)	31,789	4,338	(1,089)
Unrecognized loss at end of year	68,256	38,810	36,753
Hancock Plan [Member] | Defined Benefit Plan-Postretirement [Member]
Change in benefit obligation
Benefit obligation, beginning of year	12,373	10,290
Service cost	137	124	114
Service cost defined benefit plans		125
Interest cost	611	556	565
Plan participants' contributions	346	310
Actuarial loss		2,098
Benefits paid	(1,108)	(1,006)
Benefit obligation, end of year	16,653	12,373	10,290
Change in plan assets
Fair value of plan assets, beginning of year	0	0
Employer contributions	763	696
Plan participants' contributions	346	310
Defined contributions by plan participants	345	310
Benefit payments	(1,108)	(1,006)
Fair value of plan assets, end of year	0	0	0
Funded status at end of year-net liability	(16,653)	(12,373)
Amounts recognized in accumulated other comprehensive loss
Unrecognized loss at beginning of year	5,546	3,701
Amount of (loss)/gain recognized during the year	(538)	(302)	(296)
Benefit plan (loss)/gain amortization	(489)	(253)
Net actuarial loss/(gain)	4,294	2,098
Net actuarial loss/(gain) accumulated in other comprehensive income	4,294
Unrecognized loss at end of year	9,351	5,546	3,701
Whitney Plan [Member] | Defined Benefit Plan-Postretirement [Member]
Change in benefit obligation
Benefit obligation, beginning of year	15,949
Service cost
Interest cost	480
Plan participants' contributions	523
Actuarial loss	1,645
Benefits paid	(1,143)
Benefit obligation, end of year	17,454
Change in plan assets
Fair value of plan assets, beginning of year	0
Employer contributions	620
Plan participants' contributions	523
Benefit payments	(1,143)
Fair value of plan assets, end of year	0
Funded status at end of year-net liability	(17,454)
Amounts recognized in accumulated other comprehensive loss
Unrecognized loss at beginning of year	0
Amount of (loss)/gain recognized during the year
Net actuarial loss/(gain)	1,645
Unrecognized loss at end of year	1,645
Qualified [Member] | Whitney Plan [Member] | Defined Benefit Plan-Pension [Member]
Change in benefit obligation
Benefit obligation, beginning of year	216,992
Service cost	3,751
Interest cost	6,664
Actuarial loss	40,542
Benefits paid	(3,556)
Benefit obligation, end of year	264,393
Change in plan assets
Fair value of plan assets, beginning of year	223,495
Actual return on plan assets	(5,354)
Employer contributions	10,000
Benefit payments	(3,556)
Expenses
Fair value of plan assets, end of year	224,585
Funded status at end of year-net liability	(39,808)
Amounts recognized in accumulated other comprehensive loss
Unrecognized loss at beginning of year	0
Amount of (loss)/gain recognized during the year
Net actuarial loss/(gain)	55,524
Unrecognized loss at end of year	55,524
Nonqualified [Member] | Whitney Plan [Member] | Defined Benefit Plan-Pension [Member]
Change in benefit obligation
Benefit obligation, beginning of year	14,442
Service cost	27
Interest cost	438
Actuarial loss	1,597
Benefits paid	(570)
Benefit obligation, end of year	15,934
Change in plan assets
Fair value of plan assets, beginning of year	0
Actual return on plan assets
Employer contributions	570
Benefit payments	(570)
Expenses
Fair value of plan assets, end of year	0
Funded status at end of year-net liability	(15,934)
Amounts recognized in accumulated other comprehensive loss
Unrecognized loss at beginning of year	0
Amount of (loss)/gain recognized during the year
Net actuarial loss/(gain)	1,597
Unrecognized loss at end of year	$ 1,597