Equity Method Investments - Summarized unaudited financial data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Summary financial information of equity method investments
Current assets	$ 169,209		$ 169,209			$ 145,740
Current liabilities	41,831		41,831			$ 34,187
Net revenues	37,172	$ 35,846	104,316		$ 110,103
Operating loss	13,420	10,575	26,450		35,818
Net loss	$ 5,217	$ (3,169)	$ (10,931)		$ (7,250)
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Summary financial information of equity method investments
Current assets				$ 59,866
Non-current assets				25,193
Current liabilities				50,640
Non-current liabilities				25,173
Net revenues				36,225
Operating loss				(25,030)
Net loss				$ (42,201)