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.

+ References

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.

+ References

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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
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-SubTopic 10
-Section 50
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Equity and Equity Compensation Plans - Summary of Value Assumptions (Details) - $ / shares			12 Months Ended
	Jul. 01, 2020	Jan. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life				0 years
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life			0 years	6 years 6 months	0 years
Volatility			0.00%	33.76%	0.00%
Risk-free interest rate			0.00%	2.12%	0.00%
Dividend yield			0.00%	0.00%	0.00%
Weighted-average grant date fair value (in dollars per share)			$ 0	$ 3.22	$ 0
Minimum \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility					37.88%
Risk-free interest rate					1.96%
Maximum \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility					40.97%
Risk-free interest rate					2.26%
2017 Employee Stock Purchase Plan \| Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	6 months	6 months
Volatility	101.06%	43.65%
Risk-free interest rate	0.17%	1.57%
Dividend yield	0.00%	0.00%
Weighted-average grant date fair value (in dollars per share)	$ 17.48	$ 5.77