Basis of Presentation and Summary of Significant Accounting Policies - Revenue Recognition (Detail)	12 Months Ended
Dec. 31, 2021
Accounting Standards Update 2014-09
Disaggregation Of Revenue [Line Items]
Revenue, performance obligation, description of payment terms	The Company invoices its clients monthly for the purchases occurring during the month. Invoice payment terms, negotiated on a client-by-client basis, are typically between 30 to 90 days. However, for certain agency clients with sequential liability terms, payments are not due to the Company until such agency client has received payment from its clients who are advertisers.

Description of payment terms in contract with customer. Includes, but is not limited to, timing of payment, existence of financing component, variability of consideration and constraint on variable consideration.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

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Balance Type:	na
Period Type:	duration