STOCK-BASED COMPENSATION - Restricted Shares and Restricted Stock Unit Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
PBRSUs
Restricted Stock and Restricted Stock Units
Outstanding at beginning of year (in shares)	594,000
Granted (in shares)	191,000
Vested (in shares)	(119,000)
Forfeited (in shares)	(116,000)
Outstanding at end of year (in shares)	550,000	594,000
Weighted-Average Fair Value
Outstanding at beginning of year (in dollars per share)	$ 21.07
Granted (in dollars per share)	21.00
Vested (in dollars per share)	21.97
Forfeited (in dollars per share)	19.57
Outstanding at end of year (in dollars per share)	$ 19.62	$ 21.07
MBRSUs
Restricted Stock and Restricted Stock Units
Outstanding at beginning of year (in shares)	289,000
Granted (in shares)	125,000
Vested (in shares)	(79,000)
Forfeited (in shares)	(24,000)
Outstanding at end of year (in shares)	311,000	289,000
Weighted-Average Fair Value
Outstanding at beginning of year (in dollars per share)	$ 13.30
Granted (in dollars per share)	11.46	$ 14.75	$ 13.87
Vested (in dollars per share)	10.51
Forfeited (in dollars per share)	13.30
Outstanding at end of year (in dollars per share)	$ 13.26	$ 13.30
Restricted Stock
Restricted Stock and Restricted Stock Units
Outstanding at beginning of year (in shares)	896,000
Granted (in shares)	937,000
Vested (in shares)	(228,000)
Forfeited (in shares)	(109,000)
Outstanding at end of year (in shares)	1,496,000	896,000
Weighted-Average Fair Value
Outstanding at beginning of year (in dollars per share)	$ 21.27
Granted (in dollars per share)	20.64
Vested (in dollars per share)	22.25
Forfeited (in dollars per share)	20.74
Outstanding at end of year (in dollars per share)	$ 20.76	$ 21.27

No definition available.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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- Definition

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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- Definition

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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- Definition

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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- Definition

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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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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