Stockholders' Equity - Restricted Stock Units - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Unrecognized stock compensation expense	$ 46.3		$ 46.3
Expected weighted average period to recognize unrecognized stock compensation expense			1 year 11 months 1 day
Restricted Stock Units
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Unrecognized stock compensation expense	226.1		$ 226.1
Expected weighted average period to recognize unrecognized stock compensation expense			2 years 10 months 20 days
Intrinsic value of restricted stock units vested during the period	$ 33.6	$ 2.9	$ 64.4	$ 3.2

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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

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

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

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Intrinsic value of vested award under share-based payment arrangement. Excludes share and unit options.

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