Stockholders' Equity - Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Stock-based Compensation Expense
Stock-based compensation expense	$ 13,794	$ 8,686
Stock options
Stock-based Compensation Expense
Unrecognized stock-based compensation expense	$ 17,959
Weighted-average amortization period	3 years
Restricted stock units
Stock-based Compensation Expense
Unrecognized stock-based compensation expense	$ 144,678
Weighted-average amortization period	3 years 2 months 12 days
ESPP
Stock-based Compensation Expense
Unrecognized stock-based compensation expense	$ 471
Weighted-average amortization period	1 month 6 days
Cost of revenue
Stock-based Compensation Expense
Stock-based compensation expense	$ 1,989	1,229
Research and development
Stock-based Compensation Expense
Stock-based compensation expense	2,806	1,470
Sales and marketing
Stock-based Compensation Expense
Stock-based compensation expense	4,106	2,249
General and administrative
Stock-based Compensation Expense
Stock-based compensation expense	$ 4,893	$ 3,738

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

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