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

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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 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 estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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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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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Expected term of 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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Common Stock and Stock-Based Compensation Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4.8	$ 7.6	$ 7.3	$ 8.4	$ 7.5	$ 5.5	$ 19.7	$ 21.4
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period							10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							3 years
Number of Shares Granted							300,000
Weighted Average Grant-Date Fair Value per Award							$ 5.26
Exercise price							$ 21.61
Risk-free interest rate							1.48%
Expected life (in years)							6 years 6 months
Equity volatility							35.00%
Dividend yield							3.42%
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Granted							988,309
Weighted Average Grant-Date Fair Value per Award							$ 18.59
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							1 year
Number of Shares Granted							20,939
Weighted Average Grant-Date Fair Value per Award							$ 18.51
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							3 years
Number of Shares Granted							444,252
Weighted Average Grant-Date Fair Value per Award							$ 20.31
Minimum \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							3 years
Maximum \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							4 years