Retirement Plans (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Increase in the fair value of plan assets	$ 1,600,000
Increase in projected benefit obligation	7,600,000
Expected long-term rate of return on assets	8.00%
Target allocation of percentage, equity securities	60.00%
Target allocation of percentage, debt securities	40.00%
Discount rate on benefit obligation	4.41%	5.09%
Age limit of retired employees to receive company subsidy	64
Postretirement benefit liability	1,900,000	1,800,000
Postretirement benefit expense	100,000	200,000	200,000
Assumed health care cost trend rate used in measuring the post retirement benefit obligation	8.50%
Ultimate rate of health care cost trend	5.00%
Year on which rate declining to ultimate rate	2018
Percent of change in health care trend rate	1.00%
Change in health care trend rate would change benefit obligation	200,000
Change in health care trend rate would change aggregate service and interest cost	100,000
Pre-Age Retirees [Member]
Defined Benefit Plan Disclosure [Line Items]
Age eligibility for retired employees to participate in health care plans	65
Grandfathered Post-Age Retirees [Member]
Defined Benefit Plan Disclosure [Line Items]
Age eligibility for retired employees to participate in health care plans	65
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	(44,246,000)	(36,690,000)	(34,760,000)
Defined benefit cost excluding settlement charges	1,912,000	1,548,000	1,479,000
Expected long-term rate of return on assets	8.00%	8.00%
Estimated for future contributions	2,600,000
Accumulated benefit obligation	40,300,000	32,600,000
Discount rate on benefit obligation	4.41%	5.09%
Defined contribution	2,048,000	1,118,000
Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	(1,907,000)	(1,837,000)	(1,783,000)
Defined benefit cost excluding settlement charges	147,000	163,000	184,000
Estimated for future contributions	100,000
Discount rate on benefit obligation	3.91%	4.56%
Defined contribution	14,000	(6,000)
Benefit Equalization Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated for future contributions	200,000
Accumulated benefit obligation	3,300,000	2,900,000
Prepaid pension cost	300,000	200,000
Supplemental Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Payoff of Company's SERP obligation		700,000
401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan generally provides for employee salary deferral contributions		17.00%
Matching contribution contributed by the company under the terms of the plan	50.00%
Percent of maximum contribution by the employer for eligible employee compensation for participant employee under the plan	3.00%
Percent of maximum contribution by the employer for eligible employee compensation for non participant employee under the plan	6.00%
Percent of maximum additional discretionary matching contribution by the employer up to the maximum eligible employee compensation	30.00%
Defined contribution	$ 2,700,000	$ 2,100,000	$ 2,000,000