Defined Benefit Pension Plans Expected Future Annual Benefit Payments (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Defined Benefit Plan [Abstract]
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 3,801
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	3,124
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	3,744
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	4,329
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	4,511
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 28,121