Stock Plans and Stock-Based Compensation - Restricted Stock Units - Additional Information (Details) - USD ($) $ / shares in Units, $ 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]
Stock-based compensation expense	$ 13,351	$ 8,301	$ 34,939	$ 24,094
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, number of stock unit grants in period			251,439
Stock-based compensation expense	5,800	$ 3,700	$ 15,100	$ 12,000
Number of stock units vested			309,282
Weighted-average grant date fair values of units granted			$ 120.09	$ 81.65
Fair values of stock units			$ 17,800	$ 11,600
Unrecognized compensation expense	$ 47,000		$ 47,000
Weighted-average amortization period			2 years 5 months 19 days

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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