INCOME TAXES (Summary of Tax Carryforwards) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Internal Revenue Service (IRS)
Income Tax Contingency [Line Items]
Federal Net Operating Loss	$ 263
Tax Credits	26
Investment Tax Credits	34
State Tax Jurisdiction
Income Tax Contingency [Line Items]
Tax Credits	$ 8

The noncurrent portion of the reserve for accumulated deferred investment tax credits as of the balance sheet date. This is the remaining investment credit, which will reduce the cost of services collected from ratepayers by a ratable portion over the investment's regulatory life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 27
-URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e32262-109318

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 255
-SubTopic 10
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=82838779&loc=d3e2408-110839

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.26(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

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The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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