Employee Benefit Plans - Summary of Stock-based Compensation Expense Recognized in Financial Statements (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Sep. 25, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized	$ 89,900	$ 15,154	$ 8,752	$ 30,265	$ 17,292
Capitalized stock-based compensation expense		1,078	428	2,031	756
Stock-based compensation expense		16,232	9,180	32,296	18,048
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized		991	646	2,087	1,304
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized		5,629	2,966	10,395	6,413
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized		3,016	1,147	5,796	1,915
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense, net of amounts capitalized		$ 5,518	$ 3,993	$ 11,987	$ 7,660