INCENTIVE PLANS (Summary of Activity for Nonvested Performance/Restricted Share Units) (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Number of Shares, Beginning Balance	244,904
Target Number of Shares, Granted	117,740
Target Number of Shares, Vested	(112,302)
Target Number of Shares, Canceled/forfeited	(6,483)
Target Number of Shares, Ending Balance	243,859	244,904
Weighted-average Grant Date Fair Value, Beginning Balance	$ 113.55
Weighted-average Grant Date Fair Value, Granted	133.95	$ 110.39	$ 117.20
Weighted-average Grant Date Fair Value, Vested	117.19
Weighted-average Grant Date Fair Value, Canceled/forfeited	120.66
Weighted-average Grant Date Fair Value, Ending Balance	$ 121.53	$ 113.55
Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Number of Shares, Beginning Balance	211,930
Target Number of Shares, Granted	82,271
Target Number of Shares, Vested	(86,302)
Target Number of Shares, Canceled/forfeited	(7,746)
Target Number of Shares, Ending Balance	200,153	211,930
Weighted-average Grant Date Fair Value, Beginning Balance	$ 108.34
Weighted-average Grant Date Fair Value, Granted	133.95	$ 110.39	$ 117.20
Weighted-average Grant Date Fair Value, Vested	102.12
Weighted-average Grant Date Fair Value, Canceled/forfeited	119.63
Weighted-average Grant Date Fair Value, Ending Balance	$ 121.11	$ 108.34

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
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
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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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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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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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- 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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