Employee Stock Benefit Plans - Stock Benefit Plans (Details) - shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2010
2010 Plan \| Employee Stock Purchase Plan
Stock Benefit Plans
Purchase price as a percentage of fair market value of a share of common stock on the first or last day of an offering period (as a percent)		85.00%
Offering period		6 months
Shares reserved for issuance (in shares)		400,000
Threshold number of additional shares available for future grant (in shares)	1,000,000
Shares available for future grant (in shares)	4,913,030
2010 Plan \| Employee Stock Purchase Plan \| Class A common stock
Stock Benefit Plans
Percentage for the threshold number of additional shares available for future grant, expressed as percentage of common stock outstanding on the last day of the immediately preceding fiscal year (as a percent)	1.00%
2019 Equity plan
Stock Benefit Plans
Shares available for future grant (in shares)	10,954,595
2019 Equity plan \| Class A common stock
Stock Benefit Plans
Shares reserved for issuance (in shares)	10,000,000
2005 Equity Plan
Stock Benefit Plans
Shares available for future grant (in shares)	0
2019 Equity Plan and 2010 Purchase Plan
Stock Benefit Plans
Shares available for future grant (in shares)	15,867,625

Represents the offering period under the equity-based compensation plan.

No definition available.

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- Definition

Represents the threshold number of additional shares available for future grant under the equity-based compensation plan.

+ References

No definition available.

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- Definition

Represents the percentage to be used for the threshold number of additional shares available for future grant under the equity-based compensation plan, expressed as a percentage of common stock outstanding on the last day of the immediately preceding fiscal year.

+ References

No definition available.

+ Details

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- Definition

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

+ References

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 (a)(3)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

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