Commitments And Contingencies (Nuclear Insurance) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Long-term Purchase Commitment [Line Items]
Additional annual insurance premium due in conjunction with prolonged outage	$ 44
Full insurance policy limit	3,200
Humboldt Bay Unit 3 liability insurance	53
Coverage for purchased public liability insurance, per incident	375
Diablo Canyon [Member]
Long-term Purchase Commitment [Line Items]
Amount of property damage and business interruption coverage provided by NEIL for Diablo Canyon	3,200
Amount of property damage coverage provided by NEIL	2,700
Business interruption	490
Maximum public liability per nuclear incident under Price-Anderson Act	12,600
Maximum available public liability insurance for Diablo Canyon as required by Price-Anderson Act	375
Maximum public liability claims amount per nuclear event	12,600
Maximum total payment incurred per event under the loss sharing program	235
Maximum annual payment incurred per event under the loss sharing program	35
Humboldt Bay Unit [Member]
Long-term Purchase Commitment [Line Items]
Amount of property damage coverage provided by NEIL	131
Amount of indemnification from the NRC for public liability arising from nuclear incidents	500
Amount of liability insurance for Humboldt bay Unit 3	$ 53