Income taxes - Schedule of Components of Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S.	$ (489,091)	$ (649,172)	$ (440,473)
Foreign	(128,918)	(140,981)	(114,965)
Loss before income taxes	$ (618,009)	$ (790,153)	$ (555,438)