DERIVATIVE FINANCIAL INSTRUMENTS - CASH FLOW HEDGES (Details) $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedges to be reclassified from AOCI within 12 months	$ 13
Maximum remaining term of cash flow hedges	14 years
Equity Method Investee [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Maximum remaining term of cash flow hedges	18 years
San Diego Gas and Electric Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Maximum remaining term of cash flow hedges	1 year
Southern California Gas Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedges to be reclassified from AOCI within 12 months	$ 1
Noncontrolling Interest [Member] \| Otay Mesa VIE [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on cash flow hedges to be reclassified from AOCI within 12 months	$ 7

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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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.

+ References

No definition available.

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Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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