Accounting Policies - VIEs, Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Revenue	$ 49,809	$ 91,947	$ 61,205
Gross profit	9,898	15,194	5,760
Net income (loss)	$ (1,374)	$ 3,432	$ (3,075)