Pension Plans and Postretirement Benefit Plan (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Interest Cost	$ 1,305,000	$ 1,294,000	$ 3,914,000	$ 3,883,000
Expected Return on Plan Assets	(1,612,000)	(1,642,000)	(4,837,000)	(4,926,000)
Amortization of Net Actuarial Losses (Gains)	830,000	724,000	2,492,000	2,172,000
Net Periodic Benefit Cost	523,000	376,000	1,569,000	1,129,000
Employer's contribution to pension and post retirement benefit plans	100,000		400,000
Expected employer's contribution to pension and post retirement benefit plans	500,000		500,000
Postretirement Benefits
Net periodic benefit cost for pension plans and the postretirement benefit plan
Service Cost	123,000	117,000	369,000	352,000
Interest Cost	359,000	439,000	1,078,000	1,318,000
Amortization of Prior Service Credit	(53,000)	(53,000)	(160,000)	(160,000)
Amortization of Net Actuarial Losses (Gains)		(76,000)	(1,000)	(228,000)
Net Periodic Benefit Cost	429,000	427,000	1,286,000	1,282,000
Employer's contribution to pension and post retirement benefit plans	200,000		600,000
Expected employer's contribution to pension and post retirement benefit plans	$ 1,300,000		$ 1,300,000