Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Non-current assets (liabilities)
Non-current assets	$ 4,344
Non-current liability		$ (2,364)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Non-current assets (liabilities)
Non-current assets	0
Non-current liability		0
Significant Other Observable Inputs (Level 2)
Non-current assets (liabilities)
Non-current assets	4,344
Non-current liability		(2,364)
Significant Unobservable Inputs (Level 3)
Non-current assets (liabilities)
Non-current assets	$ 0
Non-current liability		$ 0