Acquisitions - Additional Information (Detail) - USD ($)					1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 01, 2021	Sep. 01, 2021	Jul. 01, 2021	Oct. 13, 2020	Apr. 30, 2022	Jan. 31, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Mar. 31, 2022
Business Acquisition [Line Items]
Change in fair value of contingent consideration							$ 734,000		$ 6,810,000
Net revenue							241,014,000	$ 199,008,000	$ 659,881,000	$ 526,298,000
Cisneros Interactive Noncontrolling Ownership
Business Acquisition [Line Items]
Noncontrolling interest				49.00%
Cisneros Interactive
Business Acquisition [Line Items]
Business acquisition date				Oct. 13, 2020
Ownership interest acquired		100.00%		51.00%
Aggregate cash consideration				$ 29,900,000
Business acquisition description of acquired entity									Subject to the terms of the Put and Call Agreement, if certain minimum EBITDA targets are met, the Sellers had the right (the “Put Option”), between March 15, 2024 and June 13, 2024, to cause the Company to purchase all (but not less than all) the remaining 49% of the issued and outstanding shares of Cisneros Interactive stock at a purchase price to be based on a pre-determined multiple of six times Cisneros Interactive’s 12-month EBITDA in the preceding calendar year. The Sellers also had the right to exercise the Put Option upon the occurrence of certain events, between March 2022 and April 2024.
Redeemable noncontrolling interest				30,800,000
Accounts receivables assets acquired, fair value				50,500,000
Gross amount account receivables asset acquired				54,000,000.0
Amount due under contract expected to be uncollectible				3,500,000
Increase in other assets				2,100,000
Increase in deferred tax				300,000
Decrease in goodwill				$ 1,800,000
Gain Loss on Acquisition of Minority Interest		$ 0
Accelerated earn-out based on EBITDA						$ 14,700,000			$ 21,700,000
Aggregate amount earn-out based on EBITDA					$ 28,900,000
Fair value of the contingent consideration recognized		$ 84,400,000					38,700,000		38,700,000
Contingent consideration current							26,700,000		26,700,000
Contingent consideration noncurrent liabilities							12,000,000.0		12,000,000.0
Change in fair value of contingent consideration							5,900,000		6,900,000
Net revenue							128,800,000	116,600,000	366,100,000	320,000,000.0
Net Income							$ 4,300,000	4,800,000	$ 14,700,000	13,400,000
Remaining ownership interest acquired		49.00%					49.00%		49.00%
Business combination consideration, transferred		$ 10,000,000
Cisneros Interactive | Maximum
Business Acquisition [Line Items]
Period of discounted cost of debt rate		3 years
Business combination consideration, transferred		$ 10,000,000
Cisneros Interactive | Maximum | Discount Rate
Business Acquisition [Line Items]
Discounted cost of debt rate		0.072
Cisneros Interactive | Minimum | Discount Rate
Business Acquisition [Line Items]
Discounted cost of debt rate		0.065
Cisneros Interactive | Put Option
Business Acquisition [Line Items]
Agreed future ownership Interest acquired				49.00%
Cisneros Interactive | Call Option
Business Acquisition [Line Items]
Agreed future ownership Interest acquired				49.00%
Business acquisition description of acquired entity									Additionally, subject to the terms of the Put and Call Agreement, the Company had the right (the “Call Option”), in calendar year 2024, to purchase all (but not less than all) the remaining 49% of the issued and outstanding shares of Cisneros Interactive stock at a purchase price to be based on a pre-determined multiple of six times of Cisneros Interactive’s 12-month EBITDA in calendar year 2023.
MediaDonuts
Business Acquisition [Line Items]
Business acquisition date			Jul. 01, 2021
Ownership interest acquired			100.00%				100.00%		100.00%
Aggregate cash consideration			$ 15,100,000
Accounts receivables assets acquired, fair value			9,900,000
Gross amount account receivables asset acquired			10,200,000
Amount due under contract expected to be uncollectible			$ 300,000
Period of discounted cost of debt rate			3 years
Fair value of the contingent consideration recognized							$ 17,100,000		$ 17,100,000
Contingent consideration current							5,100,000		5,100,000
Contingent consideration noncurrent liabilities							12,000,000.0		12,000,000.0
Change in fair value of contingent consideration							2,000,000.0		1,300,000
Net revenue							21,200,000	12,100,000	57,200,000
Net Income							$ 400,000		$ 2,800,000	0
Business combination consideration, transferred			$ 17,100,000
Decrease in purchase consideration								$ 1,200,000
Business combination, contingent earn-out payments			7,400,000
Total purchase price for acquisition, including fair value of contingent consideration			36,200,000
Acquisition fees and costs										$ 700,000
Fair value of contingent consideration recognized			$ 20,300,000
MediaDonuts | Maximum | Discount Rate
Business Acquisition [Line Items]
Discounted cost of debt rate			0.067
MediaDonuts | Minimum | Discount Rate
Business Acquisition [Line Items]
Discounted cost of debt rate			0.058
365 Digital
Business Acquisition [Line Items]
Business acquisition date	Nov. 01, 2021
Ownership interest acquired	100.00%						100.00%		100.00%
Aggregate cash consideration	$ 1,900,000
Purchase price adjusted based on EBITDA											$ 3,500,000
Accounts receivables assets acquired, fair value	1,100,000
Gross amount account receivables asset acquired	1,100,000
Fair value of the contingent consideration recognized							$ 600,000		$ 600,000
Contingent consideration noncurrent liabilities							600,000		600,000
Change in fair value of contingent consideration							3,200,000		1,400,000
Net revenue							2,900,000		7,800,000
Net Income							$ 0.0		$ 100,000
Total purchase price for acquisition, including fair value of contingent consideration	5,500,000
Fair value of contingent consideration recognized	$ 2,000,000.0
365 Digital | Maximum
Business Acquisition [Line Items]
Period of discounted cost of debt rate	3 years
365 Digital | Maximum | Discount Rate
Business Acquisition [Line Items]
Discounted cost of debt rate	0.083
365 Digital | Minimum | Discount Rate
Business Acquisition [Line Items]
Discounted cost of debt rate	0.076