Employee Benefit Plans Amounts Recognized on Balance Sheet Table (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 1,190	$ 740
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Current liabilities	(340)	(830)
Noncurrent liabilities	(8,120)	(11,290)
Net liability recognized at December 31	$ (7,270)	$ (11,380)