Pension and Other Postretirement Benefit Plans (Amounts recognized in balance sheet) (Details) - Swiss Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net long-term pension asset	$ 11,712	$ 8,887
Accumulated other comprehensive loss consists of the following:
Net prior service cost	782	779
Net loss	1,391	3,113
Accumulated other comprehensive loss before taxes	2,173	3,892
Actuarial loss before taxes	$ 119	$ (2,425)	$ 1,262