Equity Method Investments - Summarized unaudited financial data (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Dec. 31, 2019
Summary financial information of equity method investments
Current assets	$ 156,385		$ 156,385			$ 145,740
Current liabilities	36,475		36,475			$ 34,187
Net revenues	34,735	$ 39,147	67,144		$ 74,257
Operating loss	8,964	14,084	13,030		25,243
Net loss	$ (6,605)	$ (2,348)	$ (16,148)		$ (4,081)
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Summary financial information of equity method investments
Current assets				$ 51,440
Non-current assets				23,920
Current liabilities				104,825
Non-current liabilities				23,158
Net revenues				23,785
Operating loss				(20,438)
Net loss				$ (34,119)