Other Postretirement Benefits (Amounts Recognized in the Consolidated Financial Statements) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued post retirement liability: Current portion	$ (360)	$ (372)	$ (395)
Accrued post retirement liability: Long term portion	(1,016)	(1,313)	(1,566)
Net amount recognized	(1,573)	(1,893)	(2,116)
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued post retirement liability: Current portion	(294)	(368)	(368)
Accrued post retirement liability: Long term portion	(6,908)	(7,781)	(7,834)
Pre-tax accumulated other comprehensive loss – unamortized post-retirement healthcare costs	3,150	4,251	4,521
Net amount recognized	$ (4,052)	$ (3,898)	$ (3,681)