SHARE-BASED COMPENSATION - Share and cash settled awards (Details) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Performance Based Restricted Stock and Restricted Stock Units \| Share Settled
Number of restricted stock units
Nonvested restricted stock - beginning of year (in shares)	258	232
Granted (in shares)	97	127
Vested (in shares)	(27)	(61)
Forfeited (in shares)	(39)	(40)
Nonvested restricted stock - end of year (in shares)	289	258
Weighted average grant date fair value
Nonvested restricted stock units - beginning of year (in usd per share)	$ 53.31	$ 54.54
Granted (in usd per share)	62.26	54.70
Vested (in usd per share)	64.01	53.82
Forfeited (in usd per share)	48.89	64.01
Nonvested restricted stock units - end of year (in usd per share)	$ 55.92	$ 53.31
Performance Based Restricted Stock and Restricted Stock Units \| Cash Settled
Number of restricted stock units
Nonvested restricted stock - beginning of year (in shares)	6	27
Granted (in shares)	0	0
Vested (in shares)	(6)	(12)
Forfeited (in shares)	0	(9)
Nonvested restricted stock - end of year (in shares)	0	6
Restricted Stock Units \| Share Settled
Number of restricted stock units
Nonvested restricted stock - beginning of year (in shares)	1,273	1,411
Granted (in shares)	894	523
Vested (in shares)	(561)	(487)
Forfeited (in shares)	(105)	(174)
Nonvested restricted stock - end of year (in shares)	1,501	1,273
Weighted average grant date fair value
Nonvested restricted stock units - beginning of year (in usd per share)	$ 54.32	$ 54.12
Granted (in usd per share)	58.98	54.88
Vested (in usd per share)	55.29	54.29
Forfeited (in usd per share)	57.54	54.49
Nonvested restricted stock units - end of year (in usd per share)	$ 56.50	$ 54.32
Restricted Stock Units \| Cash Settled
Number of restricted stock units
Nonvested restricted stock - beginning of year (in shares)	853	932
Granted (in shares)	1	364
Vested (in shares)	(332)	(333)
Forfeited (in shares)	(51)	(110)
Nonvested restricted stock - end of year (in shares)	471	853

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

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
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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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-Publisher FASB
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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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