Subsequent events (Details) - $ / shares	Jul. 29, 2022	Jul. 28, 2022	Jun. 30, 2022	Dec. 31, 2021
Subsequent Event
Subsequent Events [Line Items]
Repurchase of class A common stock (in shares)		4,278
Remaining amount authorized for repurchase (in shares)		540,778
Class A Stock
Subsequent Events [Line Items]
Common stock, issued (in shares)			11,270,944	12,447,036
Class A Stock | Subsequent Event
Subsequent Events [Line Items]
Quarterly dividend payable amount per share (in dollars per share)	$ 0.15
Repurchase of class A common stock (in shares)		536,500
Shares authorized for purchase as a percentage of common stock issued and outstanding		4.80%
Common stock, issued (in shares)		11,251,930
Class B Stock
Subsequent Events [Line Items]
Common stock, issued (in shares)			99,665	99,665
Class B Stock | Subsequent Event
Subsequent Events [Line Items]
Quarterly dividend payable amount per share (in dollars per share)	$ 0.15