Commitments And Contingencies (Nuclear Insurance) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Long-term Purchase Commitment [Line Items]
Maximum total payment incurred per event under the loss sharing program	$ 450
Nuclear Incident [Member]
Long-term Purchase Commitment [Line Items]
Amount of property damage and business interruption coverage provided by NEIL for Diablo Canyon	3,200
Non Nuclear Incident [Member]
Long-term Purchase Commitment [Line Items]
Amount of property damage and business interruption coverage provided by NEIL for Diablo Canyon	2,600
EMANI [Member]
Long-term Purchase Commitment [Line Items]
Full insurance policy limit	200
Potential premium obligation	3
NEIL [Member]
Long-term Purchase Commitment [Line Items]
Potential premium obligation	57
Diablo Canyon [Member]
Long-term Purchase Commitment [Line Items]
Maximum public liability per nuclear incident under Price-Anderson Act	13,500
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	255
Coverage for purchased public liability insurance, per incident	38
Humboldt Bay Unit [Member]
Long-term Purchase Commitment [Line Items]
Amount of property damage coverage provided by NEIL	131
Amount of liability insurance for Humboldt bay Unit 3	53
Humboldt Bay Unit [Member] | Nuclear Incident [Member]
Long-term Purchase Commitment [Line Items]
Amount of indemnification from the NRC for public liability arising from nuclear incidents	$ 500