STOCK-BASED COMPENSATION AND EMPLOYEE BENEFIT PLANS (Performance Stock Awards) (Details) - Performance Stock Awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance evaluation stock-based compensation	2 years
Number of Shares
Unvested, beginning of period (in shares)	190,129
Granted (in shares)	171,584
Vested (in shares)	(21,416)
Forfeited (in shares)	(126,807)
Unvested, end of period (in shares)	213,490	190,129
Weighted Average Grant-Date Fair Value
Unvested, beginning of period (in dollars per share)	$ 55.63
Granted (in dollars per share)	55.71
Forfeited (in dollars per share)	53.59
Vested (in dollars per share)	54.82
Unvested, end of period (in dollars per share)	$ 55.71	$ 55.63
Total unrecognized compensation cost	$ 3.2
Total fair value, vested in period	$ 1.2	$ 3.0	$ 1.0

Performance Evaluation Stock-Based Compensation

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Unrecognized cost of unvested share-based compensation awards.

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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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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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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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Weighted average price of options that were either forfeited or expired.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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