SHAREHOLDERS' EQUITY AND SHARE-BASED COMPENSATION - Assumptions Used to Determine the Fair Values for Performance-Based Awards (Details) - Restricted Shares and Restricted Share Units - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Monte Carlo
Equity And Share-Based Compensation
Risk-free interest rate (%)	2.47%	2.47%
Expected stock price volatility (%)	17.72%	58.90%
Expected dividend yield	0.00%	0.00%
Expected option life (in years)	3 years	3 years
Fair value (in usd per share)	$ 0	$ 20.54
Binomial
Equity And Share-Based Compensation
Risk-free interest rate (%), minimum	0.09%
Risk-free interest rate (%)		0.00%
Risk-free interest rate (%), minimum	0.27%
Expected stock price volatility (%)	80.36%	0.00%
Expected dividend yield	0.00%	0.00%
Expected option life (in years)	2 years	0 years
Fair value (in usd per share)	$ 12.58	$ 0

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

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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.

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- Definition

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

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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
-Subparagraph (f)(2)(i)
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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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