Derivative Instruments and Hedging Activities - OCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Effect of derivative instruments on earnings
Gain (Loss) Recognized in OCI	$ (573)	$ 19	$ (2,422)	$ (1,735)
Reclassified from Accumulated OCI into Earnings
Effect of derivative instruments on earnings
Gain (Loss) Reclassified from Accumulated OCI into Earnings	(795)	(28)	(1,630)	109
Foreign currency forward contracts
Effect of derivative instruments on earnings
Gain (Loss) Recognized in OCI	177	118	166	266
Foreign currency forward contracts | Reclassified from Accumulated OCI into Earnings
Effect of derivative instruments on earnings
Gain (Loss) Reclassified from Accumulated OCI into Earnings		55	67	1
Commodity futures contracts
Effect of derivative instruments on earnings
Gain (Loss) Recognized in OCI	(750)	(99)	(2,588)	(2,001)
Commodity futures contracts | Reclassified from Accumulated OCI into Earnings
Effect of derivative instruments on earnings
Gain (Loss) Reclassified from Accumulated OCI into Earnings	$ (795)	$ (83)	$ (1,697)	$ 108