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EMPLOYEE BENEFIT PLANS - Weighted average asset allocation by asset category along with target allocation (Details) - Retirement Income Plan	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	100.00%	100.00%
Target Allocation for 2018	100.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	2.90%	3.30%
Domestic Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	42.30%	25.50%
International Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	20.70%	20.80%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	23.80%	25.30%
Investments measured at net asset value
Defined Benefit Plan Disclosure [Line Items]
Percentage of plan assets	10.30%	25.10%
Minimum | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	0.00%
Minimum | Domestic Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	0.00%
Minimum | International Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	0.00%
Minimum | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	15.00%
Minimum | Investments measured at net asset value
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	0.00%
Maximum | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	3.00%
Maximum | Domestic Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	40.00%
Maximum | International Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	20.00%
Maximum | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	25.00%
Maximum | Investments measured at net asset value
Defined Benefit Plan Disclosure [Line Items]
Target Allocation for 2018	12.00%

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- Definition

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+ References

No definition available.

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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

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2446-114920

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

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