Summary of significant accounting policies - Recent pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Jan. 01, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets	$ 21,600
Operating lease liability	$ 25,337
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets		$ 25,000
Operating lease liability		$ 28,600