Stockholders' Equity - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model (Detail) - $ / shares	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 56.89	$ 54.20	$ 39.06
Risk-free interest rate	1.00%	0.60%	2.10%
Expected dividend yield	0.00%	0.00%	0.00%
Expected volatility	75.10%	74.60%	71.80%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 38.19	$ 36.83	$ 30.32
Risk-free interest rate	0.20%	0.20%	1.90%
Expected dividend yield	0.00%	0.00%	0.00%
Expected volatility	44.20%	60.30%	69.90%
Expected term (in years)	1 year 3 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days

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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- Definition

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

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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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
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-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809

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