Stock-based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Stock-based Compensation
Recorded compensation costs for the RSAs and RSUs	$ 0.8	$ 2.7
RSAs
Stock-based Compensation
Granted (in shares)	39,915	36,183
Canceled (in shares)	5,034	8,334
Weighted average grant date fair value (in dollars per share)	$ 51.41	$ 52.83
RSUs
Stock-based Compensation
Granted (in shares)	32,720	26,473
Awards issued (in shares)	41,731	62,726
Canceled (in shares)	22,936	31,177
Weighted average grant date fair value (in dollars per share)	$ 51.41	$ 52.83
Performance period	3 years
Employees \| RSAs
Stock-based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	36 months
Director [Member] \| RSAs
Stock-based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	12 months

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

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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.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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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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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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