Stockholders' Equity - Stock Option Plan - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Weighted average grant-date fair value of stock options granted	$ 54.39	$ 39.23	$ 22.96
Intrinsic value of stock options exercised	$ 470.8	$ 474.2	$ 445.9
Unrecognized stock compensation expense	$ 50.8
Expected weighted average period to recognize unrecognized stock compensation expense	1 year 9 months 10 days

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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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Amount of cost to be recognized for option under share-based payment arrangement.

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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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-Publisher FASB
-Name Accounting Standards Codification
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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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-Publisher FASB
-Name Accounting Standards Codification
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