Balance Sheet Components - Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Accrued sales and marketing expenses	$ 22,438	$ 7,204
Accrued compensation	14,458	3,825
Accrued publisher fees	12,736	0
End-user liability, net	4,358	2,789
Accrued developer revenue share	1,505	907
Short-term lease obligations	3,956	0
Other accrued expenses	10,706	4,893
Other current liabilities	$ 70,157	$ 19,618