Fair value of financial instruments - Changes in Carrying Value (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of the Company's Level 3 financial assets	$ 305,032		$ 305,032		$ 306,097
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other changes in the carrying value of assets	0	$ 0	0	$ 0
Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of the Company's Level 3 financial assets	$ 1,100		$ 1,100		$ 300