Stockholders' equity (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) shares $ / shares	Dec. 31, 2022 USD ($) $ / shares shares	Feb. 09, 2023 USD ($)	Jan. 27, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Class of Stock [Line Items]
Stock options outstanding (shares)	2,684,000	3,089,000
Common stock available for future grants (shares)	53,033,000
Stockholders' Equity Note, Outstanding Shares Less than 10% of Aggregate Shares Outstanding, Conversion Ratio	1
Stockholders' Equity Attributable to Parent | $	$ 555,846,000	$ 611,559,000			$ 615,914,000	$ 216,018,000
Stock Repurchase Program, Authorized Amount | $			$ 40	$ 100
Stock Repurchase Program, Remaining Authorized Repurchase Amount | $	$ 60,400,000
Treasury Stock, Shares, Acquired	9,931	5,967
Treasury Stock Acquired, Average Cost Per Share | $ / shares	$ 4.03	$ 6.64
Stock Repurchased During Period, Value | $	$ 40,000,000	$ 39,618,000
Treasury Stock, Value, Acquired, Cost Method | $	40,000,000	39,618,000
Treasury Stock, Common
Class of Stock [Line Items]
Stockholders' Equity Attributable to Parent | $	$ (193,231,000)	$ (153,231,000)			$ (113,613,000)	$ (113,613,000)
Common Class A [Member]
Class of Stock [Line Items]
Common stock authorized (shares)	500,000,000	500,000,000
Common stock outstanding (shares)	123,638,000	128,629,000
Common Stock, Voting Rights, Number	1
Common Stock, Conversion Ratio	1
Common Stock, Shares, Issued	123,638,000	128,629,000
Common Stock, Voting Rights	one
Common Class B [Member]
Class of Stock [Line Items]
Common stock authorized (shares)	150,000,000	150,000,000
Common stock outstanding (shares)	26,259,000	26,259,000
Common Stock, Voting Rights, Number	10
Common Stock, Shares, Issued	26,259,000	26,259,000
Common Stock, Voting Rights	ten
Restricted Stock Units (RSUs) [Member]
Class of Stock [Line Items]
Restricted stock units outstanding (shares)	11,494,000	8,727,000
Performance Shares [Member]
Class of Stock [Line Items]
Restricted stock units outstanding (shares)	824,000	686,000
Performance stock units outstanding (shares)	1,441,000
Common Stock
Class of Stock [Line Items]
Common stock available for future grants (shares)	37,414,000