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Commitments and Guarantees Unrecorded Unconditional Purchase Obligations (Details) $ in Millions | Dec. 31, 2016 USD ($)
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Capital Additions [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | $ 256
Unrecorded Unconditional Purchase Obligation, Due within One Year | 176
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 8
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 2
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 9
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 1
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 60
Long-term Contract for Purchase of Electric Power [Domain] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 2,804
Unrecorded Unconditional Purchase Obligation, Due within One Year | 221
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 157
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 181
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 256
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 239
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 1,750
Electric Transmission [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 38
Unrecorded Unconditional Purchase Obligation, Due within One Year | 7
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 6
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 5
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 4
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 4
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 12
Public Utility Districts [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 21
Unrecorded Unconditional Purchase Obligation, Due within One Year | 4
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 4
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 1
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 0
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 1
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 11
Natural gas [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 333
Unrecorded Unconditional Purchase Obligation, Due within One Year | 53
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 39
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 32
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 27
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 24
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 158
Coal and transportationSupply Agreements [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 31
Unrecorded Unconditional Purchase Obligation, Due within One Year | 17
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 9
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 5
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 0
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 0
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 0
Commitments [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 3,483
Unrecorded Unconditional Purchase Obligation, Due within One Year | 478
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 223
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 226
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 296
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 269
Unrecorded Unconditional Purchase Obligation, Due after Five Years | $ 1,991

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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308 + Details
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X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308 + Details
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X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308 + Details
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X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308 + Details
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- Definition Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308 + Details
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