Pension Plans and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Defined Benefit Plan [Member]
Service cost:
Benefit accrual	$ 0	$ 0	$ 0	$ 0
Other expenses	90	90	180	180
Interest cost	343	357	685	714
Expected return on plan assets	(559)	(606)	(1,119)	(1,212)
Settlement loss	229	459	487	918
Amortization of:
Prior service cost	0	0	0	0
Actuarial loss	400	513	801	1,026
Net periodic pension expense	503	813	1,034	1,626
Supplemental Defined Benefit Plans [Member]
Service cost:
Benefit accrual	0	0	0	0
Other expenses	0	0	0	0
Interest cost	153	167	307	335
Expected return on plan assets	0	0	0	0
Settlement loss	0	0	0	0
Amortization of:
Prior service cost	32	31	63	62
Actuarial loss	51	245	102	490
Net periodic pension expense	$ 236	$ 443	$ 472	$ 887