Nature of Business and Significant Accounting Policies (Details 7) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes from Accumulated Other Comprehensive income [Abstract]
Pension plans, beginning balance	$ (1,615)
Pension plans adjustment, before reclassification	1,286
Pension plans, reclassification	(15)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	(494)
Pension plans adjustment, after reclassification	1,271
Pension plans, ending balalnce	(344)	$ (1,615)
Cash flow hedges, beginning balance	307
Cash flow hedges adjustment, before reclassification	187
Cash flow hedges, reclassification	0
Cash flow hedges adjustment, after reclassification	(307)
Cash flow hedges, ending balance	0	307
Foreign currency translation, beginning balance	(164,643)
Foreign currency translation adjustment	51,631
Foreign currency translation, ending balance	(113,012)	(164,643)
Accumulated other comprehensive earnings, beginning balance	(165,951)
Other comprehensive earnings, before reclassifications	53,100
Other comprehensive earnings, reclassification	(509)
Other comprehensive earnings, after adjustment	52,591
Other comprehensive income (loss), available-for-sale before reclassification, net of tax	(4)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	(4)	0
Accumulated other comprehensive earnings, ending balance	$ (113,360)	$ (165,951)