Derivative Instruments (Effects of Undesignated Derivative Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Derivative [Line Items]
Gain (loss) recognized in income	$ 0	$ 462	[1]	$ 0
Foreign currency option contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in income		513
Foreign currency forward contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in income		$ (51)

[1] The individual amounts may not sum to total gain due to rounding.