Quarterly financial information (unaudited) - Schedule of Historical Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 66,243	$ 28,736	$ 982	$ 177,228	$ 143,833	$ 132,825	$ 164,023	$ 195,796	$ 273,189	$ 636,477	$ 617,013
Operating (loss) income	(54,055)	(53,556)	(86,042)	3,416	(15,403)	(16,458)	10,334	47,237	(190,237)	25,710	90,597
Net (loss) income	$ (73,752)	$ (78,604)	$ (87,458)	$ (22,556)	$ (17,924)	$ (30,461)	$ 1,040	$ 42,988	$ (262,370)	$ (4,357)	$ 18,977
(Losses) earnings per share - Basic (in dollars per share)	$ (0.55)	$ (0.58)	$ (0.67)	$ (0.17)	$ (0.14)	$ (0.23)	$ 0.01	$ 0.33	$ (1.98)	$ (0.03)	$ 0.16
Decrease in diluted loss per share (in dollars per share) (in dollars per share)	$ (0.55)	$ (0.58)	$ (0.67)	$ (0.17)	$ (0.14)	$ (0.23)	$ 0.01	$ 0.33	$ (1.98)	$ (0.03)	$ 0.16