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Discontinued Operations and Assets and Liabilities Held for Sale (Assets and Liabilities Table) (Details) (USD $) In Millions, unless otherwise specified | Jun. 30, 2013 | Dec. 31, 2012
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Assets and Liabilities of Discontinued Operations and Held For Sale [Line Items] |  |
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net |  | $ 21.5
Disposal Group, Including Discontinued Operation, Other Assets |  | 5.2
Assets of Disposal Group, Including Discontinued Operation | 0 | 26.7
Disposal Group, Including Discontinued Operation, Other Liabilities |  | 3.9
Liabilities of Disposal Group, Including Discontinued Operation | 0 | 3.9
Gas Distribution Operations [Member] |  |
Assets and Liabilities of Discontinued Operations and Held For Sale [Line Items] |  |
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net |  | 21.5
Disposal Group, Including Discontinued Operation, Other Assets |  | 4.5
Assets of Disposal Group, Including Discontinued Operation |  | 26.0
Disposal Group, Including Discontinued Operation, Other Liabilities |  | 3.3
Liabilities of Disposal Group, Including Discontinued Operation |  | 3.3
Electric Operations [Member] |  |
Assets and Liabilities of Discontinued Operations and Held For Sale [Line Items] |  |
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net |  | 0
Disposal Group, Including Discontinued Operation, Other Assets |  | 0.7
Assets of Disposal Group, Including Discontinued Operation |  | 0.7
Disposal Group, Including Discontinued Operation, Other Liabilities |  | 0.6
Liabilities of Disposal Group, Including Discontinued Operation |  | $ 0.6

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- Definition The aggregate value (measured at the lower of net carrying value or fair value less cost of disposal) for assets of a disposal group, including a component of the entity (discontinued operation), to be sold or that has been disposed of through sale, as of the financial statement date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1107-107759 + Details
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- Definition For the disposal group, including a component of the entity (discontinued operation), carrying amount as of the balance sheet date of assets not otherwise specified. + 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 For the disposal group, including a component of the entity (discontinued operation), obligations not otherwise itemized. + 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 For the disposal group, including a component of the entity (discontinued operation), carrying value (net of accumulated depreciation and any write-downs) of tangible assets that are held by an entity for use in the production or supply of goods and services, for rental to others, or for administrative purposes and that are expected to provide economic benefit for more than one year. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. + 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 The obligations arising from the sale, disposal, or planned sale in the near future (generally within one year) of a disposal group, including a component of the entity (discontinued operation). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1107-107759 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1436-107760 + Details
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