Schedule of Earnings of Equity Method Investments Within The Consolidated Statements of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Equity Method Investments And Joint Ventures [Abstract]
Earnings of equity method investments included within operating income	$ 47	$ 52
(Losses) earnings of equity method investments included within other income		(3)
Total earnings of equity method investments	$ 47	$ 49