fair value of the Company's derivative financial instruments (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Other Current Liabilities	$ (60,688,000)	$ (50,406,000)
Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Assets	8	139,000
Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Current Liabilities	(91,000)	(5,000)
Not Designated as Hedging Instrument [Member] | Sell A U D Buy U S D Fwd Contract [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Assets		18,000
Not Designated as Hedging Instrument [Member] | Sell A U D Buy U S D Fwd Contract [Member] | Other Current Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Current Liabilities		(1,000)
Not Designated as Hedging Instrument [Member] | Sell C A D Buy U S D Fwd Contract [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Assets	8,000	121,000
Not Designated as Hedging Instrument [Member] | Sell C A D Buy U S D Fwd Contract [Member] | Other Current Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other Current Liabilities	$ (91,000)	$ (4,000)