Employee Benefit Plans - SERP Plans (Details) (Supplemental Employee Retirement Plans, Defined Benefit [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 62,891	$ 53,980
Defined Benefit Plan, Benefit Obligation	68,473	61,559	57,052
Defined Benefit Plan, Service Cost	1,525	1,642
Defined Benefit Plan, Interest Cost	3,308	3,202
Defined Benefit Plan, Actuarial Net (Gains) Losses	5,602	2,961
Defined Benefit Plan, Benefits Paid	(3,521)	(3,298)
Defined Benefit Plan, Funded Status of Plan	(68,473)	(61,559)
Defined Benefit Plan, Amortization of Gains (Losses)	787	744
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	41	80
Defined Benefit Plan, Amortization of Transition Obligations (Assets)	0	29
Defined Benefit Plan, Net Periodic Benefit Cost	$ 5,661	$ 5,697
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.75%	5.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	5.00%	5.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	5.50%	5.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	5.00%	5.00%