Stockholders' Equity and Employee Benefit Plans - Summary of Stock-based Compensation Expense Recognized in Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized	$ 98,812	$ 8,422	$ 116,104	$ 26,363
Capitalized stock-based compensation expense	495	587	1,251	2,510
Stock-based compensation expense	99,307	9,009	117,355	28,873
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized	6,472	634	7,776	1,870
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized	37,490	2,799	43,903	7,065
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized	14,496	1,322	16,411	6,622
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized	$ 40,354	$ 3,667	$ 48,014	$ 10,806