Equity Method Investments - Summarized unaudited financial data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Summary financial information of equity method investments
Current assets	$ 118,605		$ 118,605			$ 188,968
Current liabilities	73,421		73,421			$ 42,657
Net revenues	50,791	$ 37,172	138,828		$ 104,316
Operating loss	(7,362)	13,420	4,882		26,450
Net loss	$ (14,801)	$ 5,217	$ 12,239		$ (10,931)
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Summary financial information of equity method investments
Current assets				$ 14,644
Non-current assets				24,666
Current liabilities				70,066
Non-current liabilities				4,860
Net revenues				8,129
Operating loss				(9,522)
Net loss				$ (24,972)