Derivatives Gain (Loss) in Statement of Finacial Position (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (798,000)	$ 116,000	$ (1,250,000)	$ (1,070,000)
Foreign currency forward contracts | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	828,000	(833,000)	(103,000)	854,000
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	698,000	(281,000)	1,072,000	457,000
Amount of Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	30,000	0	72,000	0
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)			(106,000)		$ (54,000)
Not Designated as Hedging Instrument [Member] | Foreign currency forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ 271,000	$ 172,000	$ (106,000)	$ 113,000