Retirement Plan (Effect of One Percent Change in Health Care Cost Trend Rates) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost - Effect of 1% Point Increase	$ 506
Service cost - Effect of 1% Point Decrease	(377)
Interest cost - Effect of 1% Point Increase	778
Interest cost - Effect of 1% Point Decrease	(548)
Year-end accumulated postretirement benefit obligation - Effect of 1% Point Increase	1,745
Year-end accumulated postretirement benefit obligation - Effect of 1% Point Decrease	$ (1,461)