OTHER CONTINGENCIES AND COMMITMENTS (Nuclear Insurance) (Details) $ in Millions	8 Months Ended	12 Months Ended
	Feb. 24, 2021 outage	Dec. 31, 2020 USD ($) nuclear_generating_unit
Long-term Purchase Commitment [Line Items]
Number of nuclear generating units (nuclear generating unit) | nuclear_generating_unit		2
Maximum total payment incurred per event under the loss sharing program		$ 450
Humboldt Bay Unit
Long-term Purchase Commitment [Line Items]
Amount of property damage coverage provided by NEIL		50
Amount of liability insurance for Humboldt Bay Unit 3		53
Diablo Canyon
Long-term Purchase Commitment [Line Items]
Maximum public liability per nuclear incident under Price-Anderson Act		13,800
Maximum available public liability insurance for Diablo Canyon as required by Price-Anderson Act		450
Maximum annual payment incurred per event under the loss sharing program		275
Coverage for purchased public liability insurance, per incident		$ 41
Period for inflation adjustment		5 years
Diablo Canyon | Subsequent Event
Long-term Purchase Commitment [Line Items]
Number of outages experienced | outage	4
Nuclear Incident
Long-term Purchase Commitment [Line Items]
Amount of property damage and business interruption coverage provided by NEIL for Diablo Canyon		$ 3,200
Nuclear Incident | Humboldt Bay Unit
Long-term Purchase Commitment [Line Items]
Amount of indemnification from the nuclear regulatory commission for public liability arising from nuclear incidents		500
Non-Nuclear Incident
Long-term Purchase Commitment [Line Items]
Amount of property damage and business interruption coverage provided by NEIL for Diablo Canyon		2,700
European Mutual Association for Nuclear Insurance
Long-term Purchase Commitment [Line Items]
Full insurance policy limit		200
Potential premium obligation		4
Nuclear Electric Insurance Limited
Long-term Purchase Commitment [Line Items]
Potential premium obligation		$ 43