Share-Based Compensation Plans - Summary of Valuation Assumptions for Incentive Performance Plan (Details)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Performance Shares, Liability Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.57%	1.58%
Volatility factor	59.90%	52.10%
Expected term	2 years	1 year
Performance Share, Equity Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.44%	1.97%	1.47%	1.31%	1.10%
Volatility factor	54.60%	32.60%	32.30%	28.43%	27.45%
Expected term	3 years	3 years	3 years	3 years	3 years

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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- Definition

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

+ References

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- Definition

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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No definition available.

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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