Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	$ 337,413	$ 111,775	$ 80,758
Platform operations
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	15,913	8,794	5,350
Sales and marketing
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	50,671	29,726	20,769
Technology and development
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	57,791	36,672	26,553
General and administrative
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	$ 213,038	$ 36,583	$ 28,086