Post-retirement Plans (Net Periodic Pension Expense) (Details) - USD ($) $ in Thousands	11 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,598	$ 1,511	$ 1,294	$ 1,694
Interest cost	1,979	987	787	819
Amortization of Prior Service Cost (Credit)		(3,481)	(3,482)	(3,482)
Amortization of net loss		0	0	183
Net periodic post-retirement credit		$ (983)	$ (1,401)	$ (786)
Expected return on plans assets	2,841
Net periodic pension expense	$ 2,736