Pension and Postretirement Benefit Plans Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	$ 112	$ 139
Defined Benefit Plan, Interest Cost	250	253
Defined Benefit Plan, Amortization of net loss	450	336
Defined Benefit Plan, Net Periodic Benefit Cost	812	728
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	19	15
Defined Benefit Plan, Interest Cost	65	57
Defined Benefit Plan, Amortization of net loss	0	6
Defined Benefit Plan, Net Periodic Benefit Cost	$ 84	$ 78