DERIVATIVE FINANCIAL INSTRUMENTS - DERIVATIVE INSTRUMENTS WITH CONTINGENT FEATURES (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net liability position for derivatives with credit limits	$ 1	$ 6
Additional collateral that wil be required if credit rating falls below investment grade	2
San Diego Gas and Electric Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net liability position for derivatives with credit limits	0	$ 1
Additional collateral that wil be required if credit rating falls below investment grade	$ 0