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Represents percent of derivative contracts.

+ References

No definition available.

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- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624258-113959

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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=36459792&loc=SL20226016-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Topic 210

-SubTopic 20

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-Paragraph 3

-Subparagraph (d)(2)

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

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- Definition

Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226006-175313

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-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

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-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

+ Details

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Period Type:	duration

- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Amount of increase (decrease) in fair value of financial instruments other than those that are purchased and held principally for the purpose of hedging or mitigating market risk, credit risk, legal risk, operational risk and other types of risk.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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Balance Type:	credit
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- Definition

The estimated net amount of unrealized gains or losses on price risk cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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- Details

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Note 5 - Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 5 - Derivative Instruments (Details) [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 93	$ 80
Increase (Decrease) in Risk Management Assets and Liabilities	155	(66)	(72)
Collateral Already Posted, Aggregate Fair Value	133	121
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	7
Less Than Two Years [Member] \| Natural Gas [Member]
Note 5 - Derivative Instruments (Details) [Line Items]
Percent of Derivative Contracts	100.00%
Less Than Two Years [Member]
Note 5 - Derivative Instruments (Details) [Line Items]
Derivative, Term of Contract	2 years
Expiring in Two to Five Years [Member] \| Natural Gas [Member] \| Maximum [Member]
Note 5 - Derivative Instruments (Details) [Line Items]
Derivative, Term of Contract	5 years
Expiring in Two to Five Years [Member] \| Natural Gas [Member] \| Minimum [Member]
Note 5 - Derivative Instruments (Details) [Line Items]
Derivative, Term of Contract	2 years
Expiring in Two to Five Years [Member] \| Natural Gas [Member]
Note 5 - Derivative Instruments (Details) [Line Items]
Percent of Derivative Contracts	1.00%
Weather Derivatives [Member]
Note 5 - Derivative Instruments (Details) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(7)	(5)	(14)
Maximum [Member]
Note 5 - Derivative Instruments (Details) [Line Items]
Derivative, Collateral, Obligation to Return Cash	$ 14