Equity Method Investments - Summarized unaudited financial data (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Summary financial information of equity method investments
Current assets	$ 21,192
Non-current assets	33,842
Current liabilities	52,279
Non-current liabilities	92,012
Redeemable stock and non-controlling interests	(453)
Net revenue	7,307
Operating loss	(9,501)
Net loss	$ (13,521)