Stockholders' Equity - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model (Details) - $ / shares	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in usd per share)	$ 54.92	$ 52.50	$ 56.89	$ 50.04
Risk-free interest rate	1.10%	0.40%	1.00%	0.60%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	74.90%	75.00%	75.10%	74.30%
Expected term (in years)	6 years 1 month 6 days	6 years	6 years 1 month 6 days	6 years
Unvested restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in usd per share)	$ 82.31	$ 82.33	$ 82.41	$ 82.33
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in usd per share)	$ 29.24	$ 36.18	$ 29.24	$ 36.18
Risk-free interest rate	0.10%	0.20%	0.10%	0.20%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	47.50%	65.70%	47.50%	65.70%
Expected term (in years)	1 year 3 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809

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