Summary of significant accounting policies - Contract balances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Non-current deferred revenue recognition period	5 years
Contract asset balance	$ 1,800	$ 900	$ 500
Change in Contract with Customer, Liability [Abstract]
Balance, beginning of the period	205,509	140,449	100,025
Acquisitions	5,200	0	0
Revenue earned	(160,002)	(127,915)	(85,471)
Deferral of revenue	231,421	192,975	125,895
Balance, end of the period	$ 282,128	$ 205,509	$ 140,449
Payment terms	30 days