WILDFIRE-RELATED CONTINGENCIES (2018 Camp Fire and 2017 Northern California Wildfires Accounting Charge) (Details) $ in Millions	3 Months Ended				9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) wildfire	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) wildfire	Dec. 31, 2018 USD ($)	Oct. 17, 2019 USD ($)	Aug. 02, 2019 USD ($)
Loss Contingencies [Line Items]
Wildfire-related claims	$ 0		$ 14,226		$ 0	$ 14,226
2018 Camp Fire
Loss Contingencies [Line Items]
Accrued losses	526	$ 1,900			2,400	10,500
Loss contingency liability	12,900				12,900
2017 Northern California wildfires
Loss Contingencies [Line Items]
Loss contingency liability	$ 7,500				$ 7,500
Number of fires with probable losses (wildfire) | wildfire	21				21
Loss from claims related to wildfire	$ 2,000	$ 2,000	$ 1,000	$ 2,500	$ 4,000	$ 3,500
2017 Northern California wildfires | Subsequent event
Loss Contingencies [Line Items]
Wildfire-related claims trust, amount							$ 8,400
2017 Northern California Wildfires, other than Tubbs and 37 Fires
Loss Contingencies [Line Items]
Number of fires with probable losses (wildfire) | wildfire	19				19
2018 Camp Fire and 2017 Northern California Wildfires
Loss Contingencies [Line Items]
Estimate of possible losses	$ 30,000				$ 30,000
Wildfire-related claims	$ 100				100			$ 105
Loss from claims related to wildfire					20,300
2018 Camp Fire and 2017 Northern California Wildfires, Clean-up and Fire Suppression Costs
Loss Contingencies [Line Items]
Loss from claims related to wildfire					900
2018 Camp Fire and 2017 Northern California Wildfires, Clean-up and Fire Suppression Costs | Subsequent event
Loss Contingencies [Line Items]
Wildfire-related claims trust, amount							900
2015 Butte Fire, 2017 Northern California Wildfires, and 2018 Camp Fire | Subsequent event
Loss Contingencies [Line Items]
Estimate of possible losses							$ 13,500
Subrogated Insurance Claimholders | 2018 Camp Fire and 2017 Northern California Wildfires
Loss Contingencies [Line Items]
Loss from claims related to wildfire					11,000
Professional Service Reimbursement | 2018 Camp Fire and 2017 Northern California Wildfires
Loss Contingencies [Line Items]
Loss from claims related to wildfire					47
Individual Claimholders | 2018 Camp Fire and 2017 Northern California Wildfires
Loss Contingencies [Line Items]
Loss from claims related to wildfire					7,500
Supporting Public Entities | 2018 Camp Fire and 2017 Northern California Wildfires
Loss Contingencies [Line Items]
Loss from claims related to wildfire					$ 1,000