Stock Plans and Stock-Based Compensation - Restricted Stock Units - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 8,301	$ 3,541	$ 24,094	$ 20,257
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, number of stock unit grants in period			359,474
Stock-based compensation expense	3,700	$ 2,300	$ 12,000	$ 4,400
Number of stock units vested			272,022	138,155
Unrecognized compensation expense	$ 36,300		$ 36,300
Weighted-average amortization period			2 years 6 months 18 days

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

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