v2.4.0.8

Derivative Instruments (Detail 5) (Details) (USD $) In Millions, unless otherwise specified | Jun. 30, 2014 | Dec. 31, 2013
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Derivative Instruments Subject to Master Netting Arrangement [Line Items] |  |  |  |
Derivative, Fair Value, Gross Amount Not Offset Against Collateral, Net | $ 28 |  | $ (144) |
Derivative Fair Value, Amount Not Offset Against Collateral, Net | 0 |  | 0 |
Derivative Asset, Fair Value, Amount Offset Against Collateral | 100 |  | 56 |
Derivative Asset, Fair Value, Gross Asset | 982 |  | 550 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | (749) |  | (480) |
Derivative Liability, Fair Value, Gross Liability | (954) |  | (694) |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 749 |  | 480 |
Margin/Cash (Received) Posted Subject to Master Netting Arrangement | (72) | [1] | 62 | [1]
Derivative Liability, Fair Value, Amount Offset Against Collateral | (144) |  | (138) |
Derivative, Fair Value, Amount Offset Against Collateral, Net | (44) |  | (82) |
Derivative, Collateral, Right to Reclaim Cash | 61 | [1] | 76 | [1]
Derivative, Collateral, Obligation to Return Cash | (133) | [1] | (14) | [1]
Commodity Exchange Traded Futures and Swaps Contracts [Member] |  |  |  |
Derivative Instruments Subject to Master Netting Arrangement [Line Items] |  |  |  |
Derivative Asset, Fair Value, Amount Offset Against Collateral | 0 |  | 0 |
Derivative Asset, Fair Value, Gross Asset | 681 |  | 434 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | (590) |  | (420) |
Derivative Liability, Fair Value, Gross Liability | (640) |  | (495) |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 590 |  | 420 |
Derivative Liability, Fair Value, Amount Offset Against Collateral | 0 |  | 0 |
Derivative, Collateral, Right to Reclaim Cash | 50 | [1] | 75 | [1]
Derivative, Collateral, Obligation to Return Cash | (91) | [1] | (14) | [1]
Commodity Forward Contract [Member] |  |  |  |
Derivative Instruments Subject to Master Netting Arrangement [Line Items] |  |  |  |
Derivative Asset, Fair Value, Amount Offset Against Collateral | 95 |  | 47 |
Derivative Asset, Fair Value, Gross Asset | 296 |  | 107 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | (159) |  | (60) |
Derivative Liability, Fair Value, Gross Liability | (184) |  | (70) |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 159 |  | 60 |
Derivative Liability, Fair Value, Amount Offset Against Collateral | (14) |  | (9) |
Derivative, Collateral, Right to Reclaim Cash | 11 | [1] | 1 | [1]
Derivative, Collateral, Obligation to Return Cash | (42) | [1] | 0 | [1]
Interest Rate Swap [Member] |  |  |  |
Derivative Instruments Subject to Master Netting Arrangement [Line Items] |  |  |  |
Derivative, Fair Value, Gross Amount Not Offset Against Collateral, Net | (125) |  | (120) |
Derivative Asset, Fair Value, Amount Offset Against Collateral | 5 |  | 9 |
Derivative Asset, Fair Value, Gross Asset | 5 |  | 9 |
Derivative Asset, Fair Value, Amount Not Offset Against Collateral | 0 |  | 0 |
Derivative Liability, Fair Value, Gross Liability | (130) |  | (129) |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 0 |  | 0 |
Derivative Liability, Fair Value, Amount Offset Against Collateral | (130) |  | (129) |
Derivative, Collateral, Right to Reclaim Cash | 0 | [1] | 0 | [1]
Derivative, Collateral, Obligation to Return Cash | $ 0 | [1] | $ 0 | [1]
[1] | Negative balances represent margin deposits posted with us by our counterparties related to our derivative activities that are subject to a master netting arrangement. Positive balances reflect margin deposits and natural gas and power prepayments posted by us with our counterparties related to our derivative activities that are subject to a master netting arrangement. See Note 7 for a further discussion of our collateral.

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- Definition Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226016-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41678-113959 + Details
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