Investments and fair value measurements - Investments on Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets
Fair Value	$ 493,966
Strategic investments	12,104	$ 10,000
Level 1
Assets
Cash equivalents	1,457
Strategic investments	0	0
Liabilities
Cash settled stock appreciation rights	0	0
Level 1 | U.S. government securities
Assets
Cash equivalents	0
Fair Value	0
Level 1 | Money market funds
Assets
Cash equivalents	1,457
Level 2
Assets
Cash equivalents	7,464
Strategic investments	0	0
Liabilities
Cash settled stock appreciation rights	0	0
Level 2 | U.S. government securities
Assets
Cash equivalents	7,464
Fair Value	66,052
Level 2 | Money market funds
Assets
Cash equivalents	0
Level 3
Assets
Cash equivalents	0
Strategic investments	12,104	10,000
Liabilities
Cash settled stock appreciation rights	522	$ 818
Level 3 | U.S. government securities
Assets
Cash equivalents	0
Fair Value	0
Level 3 | Money market funds
Assets
Cash equivalents	$ 0