Business Combinations - Additional Information (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended	9 Months Ended
	Apr. 15, 2021	Mar. 19, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Revenue			$ 679,953	$ 451,663		$ 1,899,255	$ 1,128,502
Cost of revenue			316,034	236,839		870,299	625,741
Gross profit			$ 363,919	$ 214,824		$ 1,028,956	$ 502,761
Other Non-current Assets
Business Acquisition [Line Items]
Content assets acquired		$ 22,500
Nielsen's Advanced Video Advertising Business
Business Acquisition [Line Items]
Business combination, date of merger agreement	Apr. 15, 2021
Preliminary purchase consideration	$ 47,400
Business combination, aggregate cash consideration	38,500
Business combination, noncash consideration	15,200
Business combination, service agreements	$ 6,300
Business combination, obligation to deliver services period	6 years
Business combination, contract terms for goods and services to be received period	6 years
Nielsen's Advanced Video Advertising Business | Maximum
Business Acquisition [Line Items]
Business acquisition measurement period	1 year
Nielsen's Advanced Video Advertising Business | General and Administrative Expenses
Business Acquisition [Line Items]
Acquisition related cost	$ 3,900
TOH Intermediate Holdings, LLC
Business Acquisition [Line Items]
Business combination, date of merger agreement		Mar. 19, 2021
Preliminary purchase consideration		$ 97,800
Revenue					$ 13,500
Gross profit					6,200
TOH Intermediate Holdings, LLC | Platform
Business Acquisition [Line Items]
Cost of revenue					$ 7,300
TOH Intermediate Holdings, LLC | General and Administrative Expenses
Business Acquisition [Line Items]
Acquisition related cost		$ 2,400