Retirement Plan (Effect of One Percent Change in Health Care Cost Trend Rates) (Details) - Defined Benefit Post-retirement Health Coverage [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Effect of One Percent Increase, Service Cost	$ 268
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service Cost	(222)
Defined Benefit Plan, Effect of One Percent Increase, Interest Cost	68
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	(58)
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	1,443
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	$ (1,254)