Defined Benefit Plans (Schedule of Korea Defined Benefit Plan Net Cost) (Details) - Korea Defined Benefit Plan $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 151
Interest cost	29
Net pension cost	180
Cost recognized as a component of compensation cost
Defined Benefit Plan Disclosure [Line Items]
Net pension cost	151
Net cost recognized in other components of defined benefit plans, net
Defined Benefit Plan Disclosure [Line Items]
Net pension cost	$ 29