Stock-based Compensation - Summary of Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation	$ 81,659	$ 7,409	$ 132,403	$ 49,666
Infrastructure and trust & safety
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation	7,797	915	13,485	3,719
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation	51,626	3,957	83,220	20,680
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation	18,929	1,872	30,176	20,304
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation	$ 3,307	$ 665	$ 5,522	$ 4,963