Market Risks and Derivative Hedge Contracts (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Derivatives, Fair Value [Line Items]
Total	$ 71,000		$ 71,000		$ 290,000
Derivative [Line Items]
Net gains associated with foreign currency derivatives	400,000	$ (1,100,000)	1,100,000	$ (1,200,000)
Forward Purchase Contract, Euro [Member]
Derivative [Line Items]
U.S. Dollar notional amount	$ 2,244,000		$ 2,244,000
Traded exchange rate	1.12		1.12
Value date	Jul. 20, 2017
Forward Purchase Contract, Pounds Sterling [Member]
Derivative [Line Items]
U.S. Dollar notional amount	$ 4,544,000		$ 4,544,000
Traded exchange rate	1.27		1.27
Value date	Jul. 20, 2017
Forward Purchase Contract, Brazil Real [Member]
Derivative [Line Items]
U.S. Dollar notional amount	$ 2,140,000		$ 2,140,000
Traded exchange rate	1.35		1.35
Value date	Jul. 20, 2017
Forward Purchase Contract, Mexican Pesos [Member]
Derivative [Line Items]
U.S. Dollar notional amount	$ 7,439,000		$ 7,439,000
Traded exchange rate	18.36		18.36
Value date	Jul. 20, 2017
Forward Sale Contract, Norwegian Krone [Member]
Derivative [Line Items]
U.S. Dollar notional amount	$ 2,516,000		$ 2,516,000
Traded exchange rate	8.42		8.42
Value date	Jul. 20, 2017
Forward Sale Contract, Mexican Pesos (2) [Member]
Derivative [Line Items]
U.S. Dollar notional amount	$ 3,619,000		$ 3,619,000
Traded exchange rate	18.36		18.36
Value date	Jul. 20, 2017
Current Assets [Member]
Derivatives, Fair Value [Line Items]
Forward sale contracts	$ 218,000		$ 218,000		81,000
Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Forward purchase contracts	0		0		(371,000)
Forward sale contracts	$ (147,000)		$ (147,000)		$ 0