BENEFITS Benefits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure
Defined Contribution Plan Employers Matching Contribution Percentage to Participants Percentage Conribution	100.00%
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 8
Defined Contribution Plan, Employer Matching Contribution, Percent	5.00%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure
Large Cap US Equitiies	32.00%
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax	$ 1
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.75%	3.71%
Fixed Income Securities	52.00%
Other Postretirement Benefits Plan [Member] \| Fixed Income Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	75.00%
Other Postretirement Benefits Plan [Member] \| Balanced Funds [Member]
Defined Benefit Plan Disclosure
Large Cap US Equitiies	54.00%
Fixed Income Securities	10.00%
Cash Fund Investments	36.00%
Savings Plan [Member]
Defined Benefit Plan Disclosure
Defined Contribution Plan, Cost	$ 2
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure
Defined Contribution Plan, Employer Matching Contribution, Percent	3.00%
Company Contributions Vested	100.00%
Company Contributions Years	five
Defined Contribution Plan, Cost	$ 1
Minimum [Member] \| Other Postretirement Benefits Plan [Member] \| Equity Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	25.00%
Minimum [Member] \| Other Postretirement Benefits Plan [Member] \| Fixed Income Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	65.00%
Maximum [Member] \| Other Postretirement Benefits Plan [Member] \| Equity Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	35.00%

Percentage of mutual fund that is invested in cash.

No definition available.

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- Definition

Percentage company contributions are vested after five years.

+ References

No definition available.

+ Details

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- Definition

Number of years of continuous service when company contributions are fully vested.

+ References

No definition available.

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- Definition

The percentage of the employer's matching contribution to a participants defined contribution plan as a matching contribution to the participants percentage contribution.

+ References

No definition available.

+ Details

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- Definition

Percentage of mutual fund that is invested in fixed income securities.

+ References

No definition available.

+ Details

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- Definition

Percentage of mutual fund that is invested in large-cap U.S. equities.

+ References

No definition available.

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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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.

+ References

No definition available.

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- Definition

Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(5)(i)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- 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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- 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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- Definition

Amount, before tax, of cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580

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