Derivatives Notional Amounts - Not Designated as Hedges (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivative [Line Items]
Notional Amount	$ 25,024		$ 25,024		$ 14,620
Gain (Loss)			64		195
Forward exchange contracts—net
Derivative [Line Items]
Gain (Loss)	(53)	$ 271	64	$ (106)
AUD / USD
Derivative [Line Items]
Notional Amount	12,300		12,300		5,800
Gain (Loss)			122		204
CNY / USD
Derivative [Line Items]
Notional Amount	3,354		3,354		5,556
Gain (Loss)			56		(24)
EUR / USD
Derivative [Line Items]
Notional Amount	2,145		2,145		0
Gain (Loss)			(159)		0
GBP / USD
Derivative [Line Items]
Notional Amount	496		496		0
Gain (Loss)			(18)		0
NZD / USD
Derivative [Line Items]
Notional Amount	4,000		4,000		0
Gain (Loss)			47		0
DKK / CHF
Derivative [Line Items]
Notional Amount	120		120		0
Gain (Loss)			7		0
AUD / NZD
Derivative [Line Items]
Notional Amount	2,602		2,602		3,264
Gain (Loss)			9		15
EUR / NOK
Derivative [Line Items]
Notional Amount	$ 7		7		0
Gain (Loss)			$ 0		$ 0