Accrual For Cash Awards To Be Settled In Shares

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Common Stock, Increase In Shares Authorized During The Period

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Share-based Compensation Arrangement By Share-based Payment Award, Fair Value Assumptions, Period Used To Determine Volatility

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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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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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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Amount of noncash expense for share-based payment arrangement.

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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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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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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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Number of additional shares authorized for issuance under share-based payment arrangement.

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Number of shares authorized for issuance under share-based payment arrangement.

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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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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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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands									1 Months Ended	7 Months Ended	9 Months Ended	12 Months Ended
	Apr. 11, 2019	Feb. 13, 2019	Oct. 29, 2018	Jul. 31, 2018	Apr. 25, 2018	Jun. 02, 2017	Apr. 30, 2017	Jun. 07, 2012	Nov. 30, 2019	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2009	Dec. 31, 2000	Jan. 31, 2018	Jun. 30, 2010	Dec. 31, 1998
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in common stock authorized (in shares)									100,000,000
Common stock, shares authorized (in shares)										200,000,000		200,000,000	100,000,000
Common stock, shares issued (in shares)										66,543,073		66,543,073	63,676,229
Common stock, shares outstanding (in shares)										63,833,243		63,833,243	60,994,944
Common stock, par value (in dollars per share)										$ 0.001		$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)										5,000,000		5,000,000	5,000,000
Preferred stock, shares issued (in shares)										0		0	0
Preferred stock, shares outstanding (in shares)										0		0	0
Preferred stock, par value (in dollars per share)										$ 0.001		$ 0.001	$ 0.001
Weighted average fair value of stock options granted (in dollars per share)												$ 12.12	$ 6.60	$ 4.25
Dividend yield												0.00%	0.00%	0.00%
Expected life (in years)												5 years	5 years	5 years
Volatility determination period (in years)												5 years
Fair value of stock options exercised												$ 8,000	$ 16,100
Stock-based compensation expense												44,105	$ 14,841	$ 8,944
Accrual for cash awards to be settled in shares										$ 19,000		$ 19,000
2010 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized and reserved for issuance (in shares)																		1,000,000
Amended and Restated 2010 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized and reserved for issuance (in shares)						2,000,000
Increase in number of shares of common stock available for issuance (in shares)						1,000,000
2019 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares of common stock available for issuance (in shares)										1,000,000
Shares of common stock available for issuance (in shares)										900,000		900,000
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized and reserved for issuance (in shares)										3,368,048		3,368,048					1,500,000
Increase in number of shares of common stock available for issuance (in shares)		618,048	250,000	500,000	500,000
Shares of common stock available for issuance (in shares)										800,000		800,000
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost										$ 22,700		$ 22,700
Weighted average recognition period of unrecognized compensation cost												2 years 4 months 24 days
Stock Option \| 1998 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized and reserved for issuance (in shares)																			5,850,000
Stock Option \| 2000 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized and reserved for issuance (in shares)																10,000,000
Increase in number of shares of common stock available for issuance (in shares)																4,150,000
Stock Option \| 2009 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares of common stock available for issuance (in shares)															6,000,000
Stock Option \| 2009 Amended Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized and reserved for issuance (in shares)	32,067,744
Increase in number of shares of common stock available for issuance (in shares)	4,250,000						4,000,000	4,250,000
Stock option term (in years)											10 years
Shares of common stock available for issuance (in shares)										4,100,000		4,100,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost										$ 76,200		$ 76,200
Weighted average recognition period of unrecognized compensation cost												2 years 9 months 18 days
Restricted Stock Units (RSUs) \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)												3 years
Restricted Stock Units (RSUs) \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)												4 years