Derivative Instruments - Designated as hedging, Financial Position (Details) - Cross Currency Interest Rate Contract [Member] - Net Investment Hedging [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 130	$ 0
Other long-term liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0	$ (4,110)