Stockholders' Equity - Stock-Based Compensation Expense Recognized in Company's Condensed Consolidated Statement of Operations (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]
Stock-based compensation expense	$ 94,335	$ 75,844	$ 172,685	$ 156,410
Cost of revenues
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	10,008	7,655	18,475	16,998
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	20,779	18,215	38,482	36,760
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 63,548	$ 49,974	$ 115,728	$ 102,652