Fair value of financial instruments - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets
Total assets	$ 544,699	$ 354,239
Liabilities
Total liabilities	2,885	4,371
Money Market Funds
Assets
Total assets	105,303	58,127
U.S. Treasury Bills and Notes
Assets
Total assets	228,144	277,341
U.S. Agency Securities
Assets
Total assets	211,252	18,771
Success Payment Liability
Liabilities
Total liabilities	2,885	4,371
Level 1
Assets
Total assets	105,303	58,127
Liabilities
Total liabilities	0	0
Level 1 | Money Market Funds
Assets
Total assets	105,303	58,127
Level 1 | U.S. Treasury Bills and Notes
Assets
Total assets	0	0
Level 1 | U.S. Agency Securities
Assets
Total assets	0	0
Level 1 | Success Payment Liability
Liabilities
Total liabilities	0	0
Level 2
Assets
Total assets	439,396	296,112
Liabilities
Total liabilities	0	0
Level 2 | Money Market Funds
Assets
Total assets	0	0
Level 2 | U.S. Treasury Bills and Notes
Assets
Total assets	228,144	277,341
Level 2 | U.S. Agency Securities
Assets
Total assets	211,252	18,771
Level 2 | Success Payment Liability
Liabilities
Total liabilities	0	0
Level 3
Assets
Total assets	0	0
Liabilities
Total liabilities	2,885	4,371
Level 3 | Money Market Funds
Assets
Total assets	0	0
Level 3 | U.S. Treasury Bills and Notes
Assets
Total assets	0	0
Level 3 | U.S. Agency Securities
Assets
Total assets	0	0
Level 3 | Success Payment Liability
Liabilities
Total liabilities	$ 2,885	$ 4,371