v2.4.0.8

Goodwill Assets (Details) (USD $) In Millions, unless otherwise specified | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2012
--- | --- | --- | ---
Goodwill And Other Intangible Assets [Line Items] |  |  |
Goodwill | $ 3,666.2 |  | $ 3,677.3
Disposal Group, Including Discontinued Operation, Goodwill |  | 11.0 |
Northern Indiana Gas Distribution [Member] |  |  |
Goodwill And Other Intangible Assets [Line Items] |  |  |
Goodwill | 17.8 |  |
Disposal Group, Including Discontinued Operation, Goodwill |  | 1.0 |
Columbia Gas Transmission Operations [Member] |  |  |
Goodwill And Other Intangible Assets [Line Items] |  |  |
Goodwill | 2,000.0 |  |
Columbia Distribution [Member] |  |  |
Goodwill And Other Intangible Assets [Line Items] |  |  |
Goodwill | 1,700.0 |  |
Disposal Group, Including Discontinued Operation, Goodwill |  | $ 10.0 |

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- Definition For the disposal group, including a component of the entity (discontinued operation), carrying amount of goodwill (adjusted for any amortization recognized prior to adoption of FAS 142 and impairment charges). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760 + Details
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- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266 + Details
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