Share-Based Compensation Plans - Weighted Average Assumptions (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing share price ( in dollars per share)	$ 8.65	$ 15.04
Expected dividend rate	0.00%	5.90%
Expected stock price volatility		22.60%
Expected stock price volatility, minimum	49.80%
Expected stock price volatility, maximum	91.50%
Risk-free interest rate		1.60%
Risk-free interest rate, minimum	0.10%
Risk-free interest rate, maximum	0.30%
Expected life (in years)		2 years
Equity Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing share price ( in dollars per share)		$ 12.05
Expected dividend rate		7.30%
Expected stock price volatility		22.90%
Expected stock price volatility, minimum	23.30%		21.50%
Expected stock price volatility, maximum	46.20%		21.80%
Risk-free interest rate		2.50%
Risk-free interest rate, minimum	0.30%		2.30%
Risk-free interest rate, maximum	0.90%		2.70%
Expected life (in years)		2 years 10 months 6 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	1 year
Minimum \| Equity Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing share price ( in dollars per share)	$ 5.03		$ 11.89
Expected dividend rate	0.00%		6.70%
Expected life (in years)	2 years 10 months 6 days		2 years 4 months 24 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	4 years
Maximum \| Equity Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing share price ( in dollars per share)	$ 13.09		$ 13.09
Expected dividend rate	6.70%		7.40%
Expected life (in years)	4 years 2 months 4 days		2 years 10 months 6 days

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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- Definition

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.

+ References

+ Details

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- Definition

The estimated measure of the maximum 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.

+ References

No definition available.

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The estimated measure of the minimum 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.

+ References

No definition available.

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- Definition

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

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

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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

Price of a single share of a number of saleable stocks of a company.

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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
-Section 50
-Paragraph 2
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-Publisher FASB
-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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