Share-Based Compensation - Summary of Share-Based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 51,566	$ 27,376	$ 137,410	$ 71,690
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	8	137	41	876
Employee stock purchase plan rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	1,719	868	4,954	2,810
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 49,839	$ 26,371	$ 132,415	$ 68,004