Retirement Plans (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Amortization of prior service cost	$ 467,000	$ 467,000	$ 467,000
Net gain (loss), net of amortization	(14,810,000)	2,271,000	2,736,000
Income tax (expense) benefit	5,674,000	(1,106,000)	(1,236,000)
Total recognized in OCI	(8,669,000)	1,632,000	1,967,000
Pension Plan
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Net gain (loss)	(16,711,000)	777,000
Amortization of prior service cost	72,000	72,000
Net gain (loss), net of amortization	2,024,000	1,601,000
Income tax (expense) benefit	5,780,000	(995,000)
Total recognized in OCI	(8,835,000)	1,455,000
Postretirement Plan
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Net gain (loss)	(123,000)	(104,000)
Amortization of prior service cost	395,000	395,000
Net gain (loss), net of amortization	0	(3,000)
Income tax (expense) benefit	(106,000)	(111,000)
Total recognized in OCI	$ 166,000	$ 177,000