Description of business, basis of presentation and summary of significant accounting policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 2,991,093	$ 2,937,780	$ 2,299,497
Subscription
Disaggregation of Revenue [Line Items]
Total revenues	1,466,433	1,286,611	1,005,030
Advertising & Marketing Services
Disaggregation of Revenue [Line Items]
Total revenues	1,428,082	1,174,774	1,226,607
Political
Disaggregation of Revenue [Line Items]
Total revenues	60,573	445,535	38,478
Other
Disaggregation of Revenue [Line Items]
Total revenues	$ 36,005	$ 30,860	$ 29,382