Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 1,364,028	$ 1,390,997	$ 1,416,722
Reportable segments | Digital Media
Disaggregation of Revenue [Line Items]
Revenues	1,072,971	1,079,172	1,069,300
Reportable segments | Digital Media | Advertising
Disaggregation of Revenue [Line Items]
Revenues	747,254	788,135	838,075
Reportable segments | Digital Media | Subscription and licensing
Disaggregation of Revenue [Line Items]
Revenues	283,473	244,694	197,354
Reportable segments | Digital Media | Other
Disaggregation of Revenue [Line Items]
Revenues	42,244	46,343	33,871
Reportable segments | Cybersecurity and Martech
Disaggregation of Revenue [Line Items]
Revenues	291,209	312,626	348,611
Reportable segments | Cybersecurity and Martech | Subscription
Disaggregation of Revenue [Line Items]
Revenues	291,209	312,626	348,611
Corporate
Disaggregation of Revenue [Line Items]
Revenues	0	0	0
Elimination of inter-segment revenues
Disaggregation of Revenue [Line Items]
Revenues	(152)	(801)	(1,189)
Elimination of inter-segment revenues | Digital Media
Disaggregation of Revenue [Line Items]
Revenues	200	800	800
Elimination of inter-segment revenues | Cybersecurity and Martech
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 400