Revenues (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenues	$ 444,252	$ 356,976	$ 1,271,480	$ 1,020,353
Point in time
Disaggregation of Revenue [Line Items]
Total revenues	13,606	8,396	30,669	19,366
Over time
Disaggregation of Revenue [Line Items]
Total revenues	430,646	348,580	1,240,811	1,000,987
Advertising | Revision of Prior Period, Reclassification, Adjustment | Revenue Correction, Subscription And Licensing To Advertising
Disaggregation of Revenue [Line Items]
Total revenues		3,200		8,800
Subscription and licensing | Revision of Prior Period, Reclassification, Adjustment | Revenue Correction, Subscription And Licensing To Advertising
Disaggregation of Revenue [Line Items]
Total revenues		(3,200)		(8,800)
Subscription and licensing | Revision of Prior Period, Reclassification, Adjustment | Revenue Correction, Subscription And Licensing To Other
Disaggregation of Revenue [Line Items]
Total revenues		(1,700)		(6,700)
Other | Revision of Prior Period, Reclassification, Adjustment | Revenue Correction, Subscription And Licensing To Other
Disaggregation of Revenue [Line Items]
Total revenues		1,700		6,700
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	444,252	356,976	1,271,480	1,020,352
Operating Segments | Digital Media
Disaggregation of Revenue [Line Items]
Total revenues	262,429	186,784	743,280	513,462
Operating Segments | Digital Media | Advertising
Disaggregation of Revenue [Line Items]
Total revenues	198,794	138,441	574,465	380,188
Operating Segments | Digital Media | Subscription and licensing
Disaggregation of Revenue [Line Items]
Total revenues	52,010	44,423	145,935	121,028
Operating Segments | Digital Media | Other
Disaggregation of Revenue [Line Items]
Total revenues	11,625	3,920	22,880	12,246
Operating Segments | Cloud Services
Disaggregation of Revenue [Line Items]
Total revenues	182,179	170,248	528,966	507,090
Operating Segments | Cloud Services | Subscription and licensing
Disaggregation of Revenue [Line Items]
Total revenues	182,087	170,233	528,699	507,021
Operating Segments | Cloud Services | Other
Disaggregation of Revenue [Line Items]
Total revenues	92	15	267	69
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	1
Elimination of inter-segment
Disaggregation of Revenue [Line Items]
Total revenues	$ (356)	$ (56)	$ (766)	$ (200)