Note 3 - Merger with Nicor (Detail) - Purchase Price Allocation of Regulatory Assets and Liabilities (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Current assets	$ 932
Other noncurrent assets, excluding goodwill	900
Current liabilities	(1,170)
Other noncurrent liabilities	(2,157)
Regulatory Assets [Member]
Current assets	36
Other noncurrent assets, excluding goodwill	586
Regulatory Liabilities [Member]
Current liabilities	(80)
Other noncurrent liabilities	$ (1,137)

The amount of acquisition cost of a business combination allocated to current assets.

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- Definition

The amount of acquisition cost of a business combination allocated to current liabilities of the acquired entity.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 98-1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 37

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The amount of acquisition cost of a business combination allocated to noncurrent assets.

+ References

+ Details

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- Definition

Amount of acquisition cost of a business combination allocated to other noncurrent liabilities not separately disclosed.

+ References

+ Details

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