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EMPLOYEE BENEFIT PLANS (Defined Contribution Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Long-Term Incentive Compensation Plan
Earning period of Long-term cash incentive plan	3 years
Incentive payments accrued for Long-Term Cash Incentive Plan	$ 6.6	$ 3.9	$ 6.7
Other Plans
Cash surrender value of life insurance policies	49.7	47.4
Recognized gains associated with changes in the cash surrender value and proceeds from life insurance policies	$ 2.6	2.9	0.3
401(k) Plan
Defined Contribution Plans
Maximum percentage of salary permitted to be deferred by plan participants	69.00%
Rate of employer match on participant contributions	50.00%
Maximum percentage of participants compensation that is eligible for 50% matching contribution	6.00%
Expense for employer contribution to defined contribution plan	$ 5.6	5.7	5.5
DC Retirement Plan
Defined Contribution Plans
Expense for employer contribution to defined contribution plan	$ 8.3	$ 5.0	$ 9.5
Period of service for participants' full vesting in the employer's contributions	3 years

X

- Definition

Amounts that were accrued at the end of the period under the Long-Term Cash Incentive Plan for payment in future periods.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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X

- Definition

The minimum period that the individual is required to perform services in order to be fully vested under the deferred compensation arrangement.

+ References

No definition available.

+ Details

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X

- Definition

Represents the recognized gains associated with changes in the cash surrender value and proceeds from life insurance policies.

+ References

No definition available.

+ Details

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X

- References

No definition available.

+ Details

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X

- Definition

Represents the earning period of incentives under the Long-Term Cash Incentive Plan.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
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X

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

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X

- Definition

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 4
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6812-107765

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Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

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X

- 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.

+ References

No definition available.

+ Details

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X

- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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X

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

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X

- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

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- Details

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- Details

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