Acquisitions - Narrative (Details) $ in Thousands					1 Months Ended									2 Months Ended	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Apr. 20, 2021 USD ($)	May 19, 2020 USD ($) lease	Apr. 06, 2020 USD ($)	Jan. 31, 2020 USD ($)	Aug. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	May 31, 2021 shares	Apr. 30, 2021 USD ($) transaction	Feb. 28, 2021 USD ($)	Jan. 31, 2021 USD ($)	Nov. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Apr. 30, 2020 USD ($) transaction developer app	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Business Acquisition [Line Items]
Business combination, equity interests issued and issuable																			$ 0	$ 38,167
Consideration transferred, liabilities incurred																			342,170	0
Transactions | transaction														2
Payments for asset acquisitions														$ 35,000
Asset acquisition, consideration transferred														$ 35,000
Development services agreement, term														2 years
Asset acquisition, earn-out term														4 years
Contingent consideration, costs																$ 12,400				26,100
Annual earn-out payment period													4 years
Apps acquired | app														2
Game developers | developer														2
Development services agreement, renewal, term														2 years
Asset acquisition, baseline revenue, cumulative amount (up to)														$ 45,000
Change in amount of contingent consideration, cash holdback, liability												$ 34,800
Change in amount of contingent consideration, cash holdback, liability, cash payment												3,400
Change in amount of contingent consideration, cash holdback and earn out, liability, fair value of common stock												106,100
Loss on extinguishments of acquisition related contingent consideration												$ 74,700			$ 0	$ 74,712			0	$ 74,712
Certain Mobile Game Apps
Business Acquisition [Line Items]
Transactions | transaction								2
Payments for asset acquisitions						$ 130,000		$ 300,000							28,800				36,800
Asset acquisition, transaction cost						4,000		6,000
Asset acquisition, consideration transferred					$ 150,000	$ 134,000		$ 306,000
Acquired asset, amortization period					6 years	9 years		8 years
Development services agreement, term						4 years		4 years
Asset acquisition, earn-out term								4 years
Asset acquisition, earn-out payment								$ 50,000
Contingent consideration, costs															9,900				97,500
2020 Asset Acquisition
Business Acquisition [Line Items]
Contingent consideration, costs															$ 700				$ 68,600
2020 Mobile App Acquisition
Business Acquisition [Line Items]
Payments for asset acquisitions										$ 60,000
2019 Asset Acquisition
Business Acquisition [Line Items]
Payments for asset acquisitions									$ 90,000
Zenlife
Business Acquisition [Line Items]
Payments for asset acquisitions													$ 160,000
Asset acquisition, consideration transferred													$ 173,300
Acquired asset, amortization period													5 years
Development services agreement, term													4 years
Asset acquisition, deferred tax liability													$ 13,300
Mobile App One
Business Acquisition [Line Items]
Acquired asset, amortization period														3 years
Mobile App Two
Business Acquisition [Line Items]
Acquired asset, amortization period														5 years
Exit Of Machine Zone Real Estate Leases
Business Acquisition [Line Items]
Number of businesses exited | lease		1
Increase (decrease) in operating lease, right-of-use asset		$ 57,600
Increase (decrease) in operating lease, liability		63,100
Leasehold improvements, write off		15,000
Adjustments to additional paid in capital, warrants issued		400
Adjust GmbH
Business Acquisition [Line Items]
Consideration transferred	$ 967,800
Consideration transferred, liabilities incurred	342,200
Consideration paid	578,000
Liabilities incurred, cash holdback	47,600
Transaction costs	3,100
Expected tax deductible amount for goodwill	692,500
Revenue of acquiree since acquisition date																		$ 49,400
Pretax loss of acquiree since acquisition date																		$ 29,600
Conversion of stock (in shares) | shares							6,320,688
Total purchase consideration	$ 967,817
Adjust GmbH | Tradename
Business Acquisition [Line Items]
Estimated useful life	5 years
Adjust GmbH | Reported Value Measurement
Business Acquisition [Line Items]
Consideration transferred	$ 980,000
Business combination, equity interests issued and issuable	352,000
Consideration transferred, liabilities incurred	$ 50,000
Geewa A S
Business Acquisition [Line Items]
Consideration transferred				$ 25,600
Consideration paid				23,500
Consideration indemnity holdback				2,100
Business combination acquisition related costs				300
Total purchase consideration				$ 25,629
Geewa A S | Tradename
Business Acquisition [Line Items]
Estimated useful life				5 years
Redemption Games
Business Acquisition [Line Items]
Consideration transferred			$ 53,700
Transaction costs			$ 600
Percentage of voting interests acquired			95.50%
Total purchase consideration			$ 56,232
Business combination, ownership interest											0.982
Fair value of minority shares			$ 2,556
Redemption Games | Tradename
Business Acquisition [Line Items]
Estimated useful life			5 years
Redemption Games | Convertible Securities Convertible Into Class A Common Stock
Business Acquisition [Line Items]
Business combination, exchange of minority shares											0.027
Redemption Games | Class A Common Stock
Business Acquisition [Line Items]
Business combination, equity interests issued and issuable											$ 4,500
Redemption Games | Minority Shares
Business Acquisition [Line Items]
Fair value of minority shares											$ 1,500
Machine Zone
Business Acquisition [Line Items]
Consideration transferred		328,600
Business combination, equity interests issued and issuable		38,200
Consideration paid		287,100
Transaction costs		2,800
Revenue of acquiree since acquisition date																	$ 64,200
Pretax loss of acquiree since acquisition date																	$ 66,200
Total purchase consideration		328,555
Business combination, settlement of receivables		3,300
Machine Zone | Intellectual property License
Business Acquisition [Line Items]
Business combination, remaining future fixed payments		$ 37,100
Estimated useful life		2 years
Machine Zone | Tradename
Business Acquisition [Line Items]
Estimated useful life		10 years