Post-retirement Plan (Net Periodic Pension Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefit earned during the period	$ 635
Interest cost on projected benefit obligations	349
Expected Return on Plan Assets	(511)
Pension Expense	473
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefit earned during the period	300	$ 324
Interest cost on projected benefit obligations	170	197
Amortization of prior service Credit	(870)	(871)
Net periodic post-retirement credit	$ (400)	$ (350)