Supplemental quarterly financial data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Data [Abstract]
Revenues	$ 470,224	$ 379,250	$ 294,371	$ 250,230	$ 188,065	$ 173,547	$ 110,588	$ 204,992	$ 1,394,075	$ 677,192	$ 837,281
Operating income	243,449	265,736	108,347	102,803	(78,031)	(167,678)	(434,052)	(181,972)	720,335	(861,733)	(408,591)
Net income (loss)	$ 216,276	$ 136,832	$ (132,661)	$ (75,439)	$ (165,932)	$ (237,432)	$ (545,455)	$ 74,646	$ 145,008	$ (874,173)	$ (342,459)
Net income (loss) per common share:
Basic (USD per share)	$ 13.07	$ 8.68	$ (10.47)	$ (6.33)	$ (14.18)	$ (20.32)	$ (46.75)	$ 6.43	$ 10.18	$ (74.92)	$ (29.61)
Diluted (USD per share)	$ 12.84	$ 8.56	$ (10.47)	$ (6.33)	$ (14.18)	$ (20.32)	$ (46.75)	$ 6.39	$ 10.03	$ (74.92)	$ (29.61)