Note 3 - Regulated Operations (Details) - Summary of Regulatory Assets and Liabilities (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Regulatory assets
Regulatory assets - current	$ 83us-gaap_RegulatoryAssetsCurrent	$ 114us-gaap_RegulatoryAssetsCurrent
Regulatory assets - long-term	631us-gaap_RegulatoryAssetsNoncurrent	705us-gaap_RegulatoryAssetsNoncurrent
Total regulatory assets	714us-gaap_RegulatoryAssets	819us-gaap_RegulatoryAssets
Regulatory liabilities
Regulatory liabilities - current	112us-gaap_RegulatoryLiabilityCurrent	183us-gaap_RegulatoryLiabilityCurrent
Regulatory liabilities - long-term	1,601us-gaap_RegulatoryLiabilityNoncurrent	1,518us-gaap_RegulatoryLiabilityNoncurrent
Total regulatory liabilities	1,713us-gaap_RegulatoryLiabilities	1,701us-gaap_RegulatoryLiabilities
Bad debt rider [Member]
Regulatory liabilities
Regulatory liabilities - current	33	41
Regulatory liabilities - long-term	12	17
Accrued natural gas costs [Member]
Regulatory liabilities
Regulatory liabilities - current	27	92
Accumulated removal costs [Member]
Regulatory liabilities
Regulatory liabilities - current	25	27
Regulatory liabilities - long-term	1,520	1,445
Other Regulatory Liabilities [Member]
Regulatory liabilities
Regulatory liabilities - current	27	23
Regulatory liabilities - long-term	13	3
Regulatory Income Tax Liability [Member]
Regulatory liabilities
Regulatory liabilities - long-term	34	27
Unamortized investment tax credit [Member]
Regulatory liabilities
Regulatory liabilities - long-term	22	26
Recoverable Environmental Remediation Costs [Member]
Regulatory assets
Regulatory assets - current	49	45
Regulatory assets - long-term	326	433
Recoverable Pension and Other Retirement Benefit Costs [Member]
Regulatory assets
Regulatory assets - current	12	9
Regulatory assets - long-term	110	99
Seasonal Rates [Member]
Regulatory assets
Regulatory assets - current	10	10
Deferred Natural Gas Costs [Member]
Regulatory assets
Regulatory assets - current	3	1
Other Regulatory Assets [Member]
Regulatory assets
Regulatory assets - current	9	49
Regulatory assets - long-term	52	36
Long-term Debt Fair Value Adjustment [Member]
Regulatory assets
Regulatory assets - long-term	74	82
Recoverable Regulatory Infrastructure Program Costs [Member]
Regulatory assets
Regulatory assets - long-term	$ 69	$ 55

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- Definition

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 340

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

+ References

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- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 405

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

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The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

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- Definition

The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.24)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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