Equity Investments - Summarized Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Current assets	$ 12,976	$ 23,325
Non-current assets	14,704	29,297
Total Assets	27,680	52,622
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Current liabilities	34,302	54,733
Non-current liabilities	62,058	83,085
Total Liabilities	96,360	137,818
Net liabilities	(68,680)	(85,196)
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Total operating revenue	115,501	158,414	$ 243,311
Operating expenses	122,459	151,523	247,384
Operating income (loss)	(6,958)	6,891	(4,073)
Net loss	$ (12,512)	$ (3,679)	$ (12,023)