Stockholders' Equity - Stock-Based Compensation Expense Recognized in Company's Condensed Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cash paid to accelerate vesting	$ 80,566	$ 49,023
Cost of revenues
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cash paid to accelerate vesting	9,343	5,012
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cash paid to accelerate vesting	18,545	13,301
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cash paid to accelerate vesting	$ 52,678	$ 30,710