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 |