Pension and Other Postretirement Benefit Plans Components of Net Periodic Pension Costs (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan, Service Cost		$ 1,352	$ 1,225
Defined Benefit Plan, Interest Cost		1,743	1,424
Defined Benefit Plan, Expected Return on Plan Assets		(752)	(451)
Defined Benefit Plan, Amortization of Transition Obligations (Assets)		(87)	(87)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	200	159	159
Defined Benefit Plan, Amortization of Gains (Losses)		326	378
Defined Benefit Plan, Net Periodic Benefit Cost		$ 2,741	$ 2,648