Pension and Other Post Retirement Benefit Plans Pension and Other Post Retirement Benefit Plans - Health Insurance Plan (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Postemployment Plan [Line Items]
Percentange of the Premiums Paid By Plan Participants	100.00%
Accrued Benefits Payable	$ 4,035	$ 4,116
Post retirement plan expense	$ 477	$ 528	$ 574
Minimum
Schedule Of Postemployment Plan [Line Items]
Age of Plan Participants	55 years
Maximum
Schedule Of Postemployment Plan [Line Items]
Age of Plan Participants	65 years