Stock-Based Compensation - Stock-Based Award Plan Activity (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 12.8	$ (0.2)	$ 29.0	$ 13.4
Unrecognized compensation expense	$ 195.1		$ 195.1
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			2 years

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

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-Name Accounting Standards Codification
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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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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