EQUITY-BASED COMPENSATION - Performance-Based Restricted Stock Awards (Details) - Restricted Stock Awards $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) Iteration $ / shares shares	Dec. 31, 2019 Iteration $ / shares shares	Dec. 31, 2018 Iteration $ / shares shares
Minimum \| Executive officers
Aggregate Current Value
Shares earned (as a percent)	0.00%
Maximum \| Executive officers
Aggregate Current Value
Shares earned (as a percent)	200.00%
Performance-based restricted stock
Number of Shares
Non-vested at the beginning of year (in shares) \| shares	755,991	708,227
Granted (in shares) \| shares	376,609	302,327
Vested (in shares) \| shares		(89,097)
Forfeited (in shares) \| shares	(210,361)	(165,466)
Non-vested at end of year (in shares) \| shares	922,239	755,991	708,227
Weighted Average Grant Date Fair Value per Share
Non-vested at beginning of year (in dollars per share)	$ 14.31	$ 14.75
Granted (in dollars per share)	9.38	12.81	$ 13.73
Vested (in dollars per share)		13.77
Forfeited (in dollars per share)	17.13	13.77
Non-vested at end of year (in dollars per share)	$ 11.65	$ 14.31	$ 14.75
Aggregate Current Value
Aggregate Current Value \| $	$ 8,309
Vesting period	3 years
Assumptions used to estimate the fair value of options granted
Expected dividend yield	8.16%	6.17%	5.33%
Expected stock price volatility	23.70%	23.20%	25.70%
Risk-free interest rate	0.53%	2.43%	2.41%
Monte Carlo iterations \| Iteration	100,000	100,000	100,000
Weighted average estimated fair value of performance-based restricted stock awards	$ 9.38	$ 12.81	$ 13.73

Monte Carlo iterations is used in valuing an option on its own shares.

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Represents the current value of equity-based compensation awards not vested. Excludes stock and unit options.

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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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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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 non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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- Definition

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.

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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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Percentage of vesting of award under share-based payment arrangement.

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