Income taxes - Pre-tax Net Loss and Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ 32,401	$ (472,107)	$ (119,409)	$ (543,734)
Provision (benefit) for income taxes	$ 17,692	$ (34,276)	$ 8,583	$ (25,297)
Effective tax rate (percent)	54.60%	7.30%	(7.20%)	4.70%