Income Taxes - Components of provision for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Provision for income tax benefit (expense)
Current	$ 151	$ 8,520	$ 5,222
Income tax benefit	$ 151	$ 8,520	$ 5,222
Effective tax rate (as a percent)	0.08%	2.97%	2.16%
Provision for income taxes on undistributed earnings of foreign subsidiaries	$ 0
Undistributed earnings		$ 0
United States
Provision for income tax benefit (expense)
Current	173	8,545	$ 5,210
Ireland
Provision for income tax benefit (expense)
Current	$ (8)	$ (13)
Effective tax rate (as a percent)	0.08%	2.97%	2.16%
United Kingdom
Provision for income tax benefit (expense)
Current	$ (14)	$ (12)	$ 12