Financial Instruments (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives - Fair Value	$ 2,963	$ 987
Liability Derivatives - Fair Value	1,521	166
Derivatives Designated as Hedging Instruments | Foreign Exchange Forward | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives - Fair Value	2,329	473
Derivatives Designated as Hedging Instruments | Foreign Exchange Forward | Other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives - Fair Value	153	166
Derivatives Designated as Hedging Instruments | Interest Rate Swap [Member] | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives - Fair Value	464
Derivatives Designated as Hedging Instruments | Interest Rate Swap [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives - Fair Value	170
Derivatives Designated as Hedging Instruments | Interest Rate Swap [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives - Fair Value	1,368
Derivatives Designated as Hedging Instruments | Cross currency interest rate swaps | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives - Fair Value		514
Derivatives Designated as Hedging Instruments | Cross currency interest rate swaps | Other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives - Fair Value		0
Derivatives not designated as hedging instruments | Foreign Exchange Forward | Other current assets
Derivatives, Fair Value [Line Items]
Asset Derivatives - Fair Value	2,915	4,459
Derivatives not designated as hedging instruments | Foreign Exchange Forward | Other current liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives - Fair Value	$ 6,970	$ 3,372