Segment Information - Reconciliation of Total Segment Operating Income to Consolidated Operating Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenues	$ 1,364,028	$ 1,390,997	$ 1,416,722
Total operating costs and expenses	1,231,417	1,192,056	1,249,382
Income from operations	132,611	198,941	167,340
Reportable segments
Segment Reporting Information [Line Items]
Total operating costs and expenses	1,179,979	1,141,865	1,189,082
Income from operations	184,049	249,132	227,640
Elimination of inter-segment revenues
Segment Reporting Information [Line Items]
Total revenues	(152)	(801)	(1,189)
Total operating costs and expenses	(152)	(801)	(1,189)
Corporate
Segment Reporting Information [Line Items]
Total revenues	0	0	0
Total operating costs and expenses	51,438	50,191	60,300
Income from operations	(51,438)	(50,191)	(60,300)
Digital Media \| Reportable segments
Segment Reporting Information [Line Items]
Total revenues	1,072,971	1,079,172	1,069,300
Total operating costs and expenses	931,980	880,240	851,807
Income from operations	140,991	198,932	217,493
Digital Media \| Elimination of inter-segment revenues
Segment Reporting Information [Line Items]
Total revenues	200	800	800
Cybersecurity and Martech \| Reportable segments
Segment Reporting Information [Line Items]
Total revenues	291,209	312,626	348,611
Total operating costs and expenses	248,151	262,426	338,464
Income from operations	43,058	50,200	10,147
Cybersecurity and Martech \| Reportable segments \| Revision of Prior Period, Adjustment
Segment Reporting Information [Line Items]
Total operating costs and expenses			19,200
Cybersecurity and Martech \| Elimination of inter-segment revenues
Segment Reporting Information [Line Items]
Total revenues	$ 0	$ 0	$ 400