Employee Benefit Plans (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 pension plan benefits [Member]
Components of net periodic benefit cost
Service cost – benefits earned during the year	$ 2	$ 12	$ 15	$ 24
Interest cost on projected benefit obligations	440	571	892	1,128
Expected return on plan assets	(684)	(803)	(1,379)	(1,595)
Amortization of prior service cost	0	0	0	0
Amortization of net loss (gain)	218	(154)	433	368
Settlement expense	747	0	747	0
Net periodic benefit cost (income)	723	(374)	708	(75)
Other postretirement benefits [Member]
Components of net periodic benefit cost
Service cost – benefits earned during the year	42	39	84	78
Interest cost on projected benefit obligations	66	76	132	152
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	40	40	80	80
Amortization of net loss (gain)	3	0	6	0
Settlement expense	0	0	0	0
Net periodic benefit cost (income)	$ 151	$ 155	$ 302	$ 310