Accounting Policies - VIEs, Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Revenue	$ 91,947	$ 61,205	$ 77,361
Gross profit	15,194	5,760	11,325
Net income (loss)	$ 3,432	$ (3,075)	$ 321