Income taxes - Reconciliation items from U.S. statutory income tax rate to the effective tax rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S. statutory income tax rate	21.00%	21.00%	21.00%
U.S. tax benefit for foreign derived intangible income	(6.10%)	(6.10%)	(4.90%)
U.S. excess tax benefit for stock compensation	(1.50%)	(2.50%)	(3.10%)
U.S. R&D tax credit	(0.90%)	(1.30%)	(1.40%)
Impact of changes in uncertain tax positions	(0.20%)	(4.00%)	(0.10%)
Other	0.60%	(0.10%)	0.90%
Effective tax rate	12.90%	7.00%	12.40%