Post-retirement Plan (Net Periodic Pension Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		8 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 1,013		$ 2,596
Interest cost on projected benefit obligations	556		1,424
Expected Return on Plan Assets	(802)		(2,053)
Pension Cost (Reversal of Cost)	767		$ 1,967
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	300	$ 324		$ 901	$ 972
Interest cost on projected benefit obligations	170	197		509	591
Amortization of prior service Credit	(870)	(871)		(2,610)	(2,613)
Net periodic post-retirement credit	$ (400)	$ (350)		$ (1,200)	$ (1,050)