Pension Plans and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Defined Benefit Plan [Member]
Service Cost
Benefit accrual
Other expenses	90	57	180	125
Interest cost	357	388	714	844
Expected return on plan assets	(606)	(556)	(1,212)	(1,210)
Settlement loss	459		918
Amortization of:
Prior service cost
Actuarial loss	513	408	1,026	888
Net periodic pension expense	813	297	1,626	647
Supplemental Defined Benefit Plans [Member]
Service Cost
Benefit accrual
Other expenses
Interest cost	167	208	335	397
Expected return on plan assets
Settlement loss
Amortization of:
Prior service cost	31	33	62	63
Actuarial loss	245	173	490	329
Net periodic pension expense	$ 443	$ 414	$ 887	$ 789