Commitments and Guarantees Unrecorded Unconditional Purchase Obligations (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Capital Additions [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	$ 934
Unrecorded Unconditional Purchase Obligation, Due within One Year	710
Unrecorded Unconditional Purchase Obligation, Due within Two Years	113
Unrecorded Unconditional Purchase Obligation, Due within Three Years	40
Unrecorded Unconditional Purchase Obligation, Due within Four Years	2
Unrecorded Unconditional Purchase Obligation, Due within Five Years	2
Unrecorded Unconditional Purchase Obligation, Due after Five Years	67
Long-term Contract for Purchase of Electric Power [Domain]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	1,483
Unrecorded Unconditional Purchase Obligation, Due within One Year	240
Unrecorded Unconditional Purchase Obligation, Due within Two Years	159
Unrecorded Unconditional Purchase Obligation, Due within Three Years	150
Unrecorded Unconditional Purchase Obligation, Due within Four Years	125
Unrecorded Unconditional Purchase Obligation, Due within Five Years	126
Unrecorded Unconditional Purchase Obligation, Due after Five Years	683
Electric Transmission [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	72
Unrecorded Unconditional Purchase Obligation, Due within One Year	22
Unrecorded Unconditional Purchase Obligation, Due within Two Years	23
Unrecorded Unconditional Purchase Obligation, Due within Three Years	22
Unrecorded Unconditional Purchase Obligation, Due within Four Years	2
Unrecorded Unconditional Purchase Obligation, Due within Five Years	2
Unrecorded Unconditional Purchase Obligation, Due after Five Years	1
Public Utility Districts [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	66
Unrecorded Unconditional Purchase Obligation, Due within One Year	8
Unrecorded Unconditional Purchase Obligation, Due within Two Years	8
Unrecorded Unconditional Purchase Obligation, Due within Three Years	7
Unrecorded Unconditional Purchase Obligation, Due within Four Years	5
Unrecorded Unconditional Purchase Obligation, Due within Five Years	5
Unrecorded Unconditional Purchase Obligation, Due after Five Years	33
Natural gas [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	122
Unrecorded Unconditional Purchase Obligation, Due within One Year	65
Unrecorded Unconditional Purchase Obligation, Due within Two Years	21
Unrecorded Unconditional Purchase Obligation, Due within Three Years	12
Unrecorded Unconditional Purchase Obligation, Due within Four Years	10
Unrecorded Unconditional Purchase Obligation, Due within Five Years	8
Unrecorded Unconditional Purchase Obligation, Due after Five Years	6
Coal and transportationSupply Agreements [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	48
Unrecorded Unconditional Purchase Obligation, Due within One Year	21
Unrecorded Unconditional Purchase Obligation, Due within Two Years	6
Unrecorded Unconditional Purchase Obligation, Due within Three Years	6
Unrecorded Unconditional Purchase Obligation, Due within Four Years	6
Unrecorded Unconditional Purchase Obligation, Due within Five Years	4
Unrecorded Unconditional Purchase Obligation, Due after Five Years	5
Operatomg leases [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	241
Unrecorded Unconditional Purchase Obligation, Due within One Year	11
Unrecorded Unconditional Purchase Obligation, Due within Two Years	9
Unrecorded Unconditional Purchase Obligation, Due within Three Years	10
Unrecorded Unconditional Purchase Obligation, Due within Four Years	10
Unrecorded Unconditional Purchase Obligation, Due within Five Years	10
Unrecorded Unconditional Purchase Obligation, Due after Five Years	191
Commitments [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation	2,966
Unrecorded Unconditional Purchase Obligation, Due within One Year	1,077
Unrecorded Unconditional Purchase Obligation, Due within Two Years	339
Unrecorded Unconditional Purchase Obligation, Due within Three Years	247
Unrecorded Unconditional Purchase Obligation, Due within Four Years	160
Unrecorded Unconditional Purchase Obligation, Due within Five Years	157
Unrecorded Unconditional Purchase Obligation, Due after Five Years	$ 986