Percentage of units earned of units granted.

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Weighted-average period over which cost not yet recognized is expected to be recognized for 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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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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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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Number of options outstanding, including both vested and non-vested options.

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Description of terms of award under share-based payment arrangement.

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Amount of cost expensed and capitalized for award under share-based payment arrangement.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Equity Incentive Plans - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	2,166,875		2,278,789
Stock-based compensation cost capitalized	$ 0.6	$ 0.2
Total intrinsic value of options exercised	7.7	$ 41.9
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation expense related to stock options	$ 8.9
Unrecognized compensation expense expected to be recognized over weighted average period	1 year 6 months
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense expected to be recognized over weighted average period	2 years 9 months 18 days
Total unrecognized compensation expense expected to be recognized	$ 374.0
Restricted Stock Units (RSUs) \| Employees \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period	3 years
Restricted Stock Units (RSUs) \| Employees \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period	4 years
Restricted Stock Units (RSUs) \| Non Employee Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options vesting period	1 year
Performance Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense expected to be recognized over weighted average period	2 years
Stock options vesting period	3 years
Total unrecognized compensation expense expected to be recognized	$ 53.3
Vesting term, description	Each PSU grant will vest in annual tranches over a three-year service period. Total PSUs earned for grants made in 2022 and 2021 may vary between 0% and 250% of the PSUs granted based on the attainment of company-specific performance targets during the related three-year period and continued service.
Service period	3 years
Performance Share Units (PSUs) \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage	0.00%
Performance Share Units (PSUs) \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage	250.00%
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	4,500,890
Shares available for future issuance	14,372,738
2006 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares subject to outstanding awards	1,093,901
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares purchased	85,926
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation expense related to stock options	$ 1.7