Acquisitions - Summary of Purchase Price Allocation (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Nov. 01, 2021	Jul. 01, 2021	Dec. 31, 2020	Oct. 13, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill	$ 71,708			$ 58,043		$ 46,511
Cisneros Interactive
Business Acquisition [Line Items]
Cash					$ 8,700
Accounts receivable					50,500
Other assets					8,300
Intangible assets subject to amortization					41,700
Goodwill					10,500
Current liabilities					(48,100)
Deferred tax					(10,900)
Redeemable noncontrolling interest					$ (30,800)
MediaDonuts
Business Acquisition [Line Items]
Cash			$ 4,300
Accounts receivable			9,900
Other assets			1,800
Intangible assets subject to amortization			22,800
Goodwill			13,400
Current liabilities			(10,100)
Deferred tax			(4,200)
Long-term liabilities			$ (1,700)
365 Digital
Business Acquisition [Line Items]
Cash		$ 500
Accounts receivable		1,100
Intangible assets subject to amortization		2,200
Goodwill		2,100
Current liabilities		(1,400)
Deferred tax		$ (600)