Stock Plans and Stock-Based Compensation - Stock Options - 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
Intrinsic value of options exercised			44,500
Intrinsic value of all outstanding options	28,200		28,200
Total unrecognized compensation cost	7,600		7,600
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,300	$ 700	$ 4,700	$ 4,700
Weighted-average amortization period			2 years 1 month 6 days

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

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Amount of cost to be recognized for option under share-based payment arrangement.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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