WILDFIRE-RELATED CONTINGENCIES (2019 Kincade Fire and 2020 Zogg Fire) (Details) $ in Millions		3 Months Ended	12 Months Ended
	Nov. 04, 2019 numberOfPeople	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Apr. 28, 2021 complaint numberOfPlaintiff plaintiff civil_case	Apr. 06, 2021 felony misdemeanor minor firefighter_structure	Sep. 27, 2020 a structure fatality injury	Oct. 23, 2019 a injury structure numberOfFatality customer
Loss Contingencies [Line Items]
Insurance settlements receivable		$ 702.0	$ 674.0
Cumulative reimbursements from insurance policies		28.0
2019 Kincade Fire
Loss Contingencies [Line Items]
Number of acres burned (acre) | a							77,758
Number of fatalities (fatality) | numberOfFatality							0
Number of injuries (injuries) | injury							4
Number of structures destroyed (structure) | structure							374
Number of residences destroyed (residence) | structure							174
Number of commercial structures destroyed (structure) | structure							11
Number of other buildings destroyed (structures) | structure							189
Number of structures damaged (structure) | structure							60
Number of residential structures damaged (structure) | structure							35
Number of commercial structures damaged (structure) | structure							1
Number of other structures damaged (structure) | structure							24
Number of people part of mandatory evacuation order (people) | numberOfPeople	200,000
Number of customers without power (customer) | customer							27,837
Potential loss contingency		800.0	625.0
Potential loss contingency, additional		175.0
Insurance settlements receivable		430.0	430.0
Cumulative reimbursements from insurance policies		0.0
2019 Kincade Fire | Subsequent event
Loss Contingencies [Line Items]
Number of complaint (complaint) | complaint				25
Number of plaintiffs represented by complaints (plaintiff) | plaintiff				535
2019 Kincade Fire | Subsequent event | Sonoma Contry District Attorney | Pacific Gas & Electric Co (Utility)
Loss Contingencies [Line Items]
Number of felonies (felony) | felony					5
Number of misdemeanors (misdemeanor) | misdemeanor					28
Number of felonies counts of recklessly causing a fire (felony) | felony					3
Number of firefighters and/or burned inhabited and other structures (firefighter/structure) | firefighter_structure					6
Number of felonies counts of emission of air contaminants (felony) | felony					2
Number of minors (minor) | minor					2
Number of misdemeanors related to carelessly or negligently throwing or placing substances that may cause a fire (misdemeanor) | misdemeanor					1
Number of misdemeanors related to negligently causing a fire (misdemeanor) | misdemeanor					1
Number of misdemeanors related to violation by a public utility (misdemeanor) | misdemeanor					3
Number of misdemeanors related to recklessly or negligently emitting air contaminants (misdemeanor) | misdemeanor					23
2020 Zogg Fire
Loss Contingencies [Line Items]
Number of acres burned (acre) | a						56,338
Number of fatalities (fatality) | fatality						4
Number of injuries (injuries) | injury						1
Number of structures destroyed (structure) | structure						204
Number of structures damaged (structure) | structure						27
Potential loss contingency		300.0	275.0
Potential loss contingency, additional		25.0
Liability insurance coverage		611.0
Insurance settlements receivable		247.0	219.0
Number of single family homes destroyed (structure) | structure						63
Cumulative reimbursements from insurance policies		28.0
Initial self-insured retention per occurrence		60.0
Legal fees		$ 7.0
2020 Zogg Fire | Maximum
Loss Contingencies [Line Items]
Liability insurance coverage			$ 867.5
2020 Zogg Fire | Subsequent event
Loss Contingencies [Line Items]
Number of complaint (complaint) | complaint				7
Number of plaintiffs represented by complaints (plaintiff) | numberOfPlaintiff				266
Number of civil cases (civil case) | civil_case				5