Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined pension plan benefits [Member]
Components of net periodic benefit cost
Service cost - benefits earned during the year	$ 12	$ 107	$ 36	$ 393
Interest cost on projected benefit obligations	564	605	1,691	1,859
Expected return on plan assets	(797)	(936)	(2,392)	(2,825)
Amortization of prior service cost	0	49	0	147
Amortization of net (gain) loss	184	448	553	1,346
Net periodic benefit cost (income)	(37)	273	(112)	920
Other postretirement benefits [Member]
Components of net periodic benefit cost
Service cost - benefits earned during the year	36	37	107	111
Interest cost on projected benefit obligations	74	81	221	243
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	40	40	121	120
Amortization of net (gain) loss	0	0	0	0
Net periodic benefit cost (income)	$ 150	$ 158	$ 449	$ 474