Retirement Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Interest Cost	$ 1,306,000	$ 1,498,000	$ 1,849,000
Defined Benefit Plan, Actual Return on Plan Assets	0	0	0
Defined Benefit Plan, Amortization of Gains (Losses)	(289,000)	534,000	2,197,000
Defined Benefit Plan, Net Periodic Benefit Cost	1,017,000	2,032,000	4,046,000
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation	31,377,000	32,891,000
Defined Benefit Plan, Interest Cost	1,306,000	1,498,000	1,849,000
Defined Benefit Plan, Actuarial Net (Gains) Losses	49,000	846,000
Defined Benefit Plan, Benefits Paid	(3,518,000)	(3,858,000)
Defined Benefit Plan, Benefit Obligation	29,214,000	31,377,000	32,891,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Defined Benefit Plan, Contributions by Employer	3,518,000	3,858,000
Defined Benefit Plan, Benefits Paid	(3,518,000)	(3,858,000)
Defined Benefit Plan, Fair Value of Plan Assets	0	0	0
Defined Benefit Plan, Funded Status of Plan	(29,214,000)	(31,377,000)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(29,214,000)	(31,377,000)
Defined Benefit Plan, Accumulated Benefit Obligation	29,214,000	31,377,000
Defined Benefit Pension Plan, Liabilities, Noncurrent	(29,214,000)	(31,377,000)
Defined Benefit Plan, Estimated Amount of Plan Participants' Future Benefits Covered by Insurance Contracts Issued by Employer or Related Parties	51,100,000	51,600,000
Cash Surrender Value of Life Insurance, Retirement Plans	37,500,000	37,300,000
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.05%	4.45%	5.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.41%	4.80%	5.97%
2012	3,646,000
2013	3,577,000
2014	3,600,000
2015	3,011,000
2016	2,760,000
Years 2017 through 2021	10,373,000
Defined Contribution Plan, Cost Recognized	$ 22,300,000	$ 20,300,000	$ 18,100,000