Retirement Plans (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Prior service cost	$ 232	$ 274
Net actuarial (gain) loss	37,240	32,932
Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive income	37,472	33,206
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Prior service cost	0	103
Net actuarial (gain) loss	35	(135)
Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive income	$ 35	$ (32)