Share-Based Compensation - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant-date fair value of stock options vested	$ 2.5	$ 2.1
Aggregate intrinsic value of stock options exercised	$ 719.0	$ 5.8
Stock options granted (in shares)	1,130,000	0
Unrecognized share-based compensation expense	$ 764.3
Weighted-average recognition period for unrecognized share-based compensation expense	3 years 1 month 6 days
2009 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance (in shares)	0
2009 Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
2009 Plan \| RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	7 years
2019 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of outstanding shares, additional reserve	5.00%
2019 Plan \| Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance (in shares)	100,443,058
2019 Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years

Common Stock, Additional Shares Reserved For Future Issuance, Percentage Of Outstanding Shares

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Aggregate number of common shares reserved for future issuance.

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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 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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Gross number of share options (or share units) granted during the period.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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