Income Taxes - Uncertain tax positions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Movement in Uncertain Tax Positions
Uncertain tax positions at the beginning of the period	$ 500,000	$ 100,000	$ 100,000
Gross increase — tax position in prior periods	0	400,000	0
Gross decrease — tax position in prior periods	0	0	0
Gross increase — current period tax position	0	0	0
Settlements, increase	0	0	0
Settlements	0	0	0
Lapse in statute of limitations	0	0	0
Foreign exchange, increase	0	0	0
Foreign exchange	0	0	0
Uncertain tax positions at the end of the period	$ 500,000	$ 500,000	$ 100,000