DERIVATIVE FINANCIAL INSTRUMENTS - NOTIONALS AMOUNTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018
Cross-currency swaps [Member]
Derivatives, Fair Value [Line Items]
Notional amount of derivative liability	$ 408	$ 408
Other foreign currency derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional amount of derivative liability	345	86
Cash Flow Hedging [Member] | Interest rate instruments [Member]
Derivatives, Fair Value [Line Items]
Notional amount of derivative liability	$ 861	$ 924
Minimum [Member] | Cross-currency swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2017
Minimum [Member] | Other foreign currency derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2017
Minimum [Member] | Cash Flow Hedging [Member] | Interest rate instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2017
Maximum [Member] | Cross-currency swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2023	Dec. 31, 2023
Maximum [Member] | Other foreign currency derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2019	Dec. 31, 2018
Maximum [Member] | Cash Flow Hedging [Member] | Interest rate instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2032	Dec. 31, 2032
Subsequent Event [Member] | Other foreign currency derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional amount of derivative liability			$ 650
San Diego Gas and Electric Company [Member] | Cash Flow Hedging [Member] | Interest rate instruments [Member]
Derivatives, Fair Value [Line Items]
Notional amount of derivative liability	$ 295	$ 305
San Diego Gas and Electric Company [Member] | Minimum [Member] | Cash Flow Hedging [Member] | Interest rate instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2017
San Diego Gas and Electric Company [Member] | Maximum [Member] | Cash Flow Hedging [Member] | Interest rate instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Maturity Date	Dec. 31, 2019	Dec. 31, 2019