Fair Value Measurements and Derivative Instruments - Balance Sheet Hedging Instruments (Details) - Foreign currency debt - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Derivative Instruments
Carrying Value of Non-derivative instrument Designated as hedging instrument	$ 284,886	$ 311,225
Long Term Debt Current
Derivative Instruments
Carrying Value of Non-derivative instrument Designated as hedging instrument	69,023	61,601
Long-term Debt
Derivative Instruments
Carrying Value of Non-derivative instrument Designated as hedging instrument	$ 215,863	$ 249,624