Fair Value Measurements (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	$ 309	$ 2,517
Liability derivatives	(1,281)	(348)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	0	0
Liability derivatives	0	0
Bank acceptances	0	0
Rabbi trust assets	2,784	2,457
Financial assets and financial liabilities, reported at fair value	2,784	2,457
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	309	2,517
Liability derivatives	(1,281)	(348)
Bank acceptances	15,281	17,698
Rabbi trust assets	0	0
Financial assets and financial liabilities, reported at fair value	14,309	19,867
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	0	0
Liability derivatives	0	0
Bank acceptances	0	0
Rabbi trust assets	0	0
Financial assets and financial liabilities, reported at fair value	0	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	309	2,517
Liability derivatives	(1,281)	(348)
Bank acceptances	15,281	17,698
Rabbi trust assets	2,784	2,457
Financial assets and financial liabilities, reported at fair value	$ 17,093	$ 22,324
Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity of bank acceptances	3 years
Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Maturity of bank acceptances	6 months