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Asset Retirement Obligations (ARO Rollforward) (Details) (USD $) In Millions, unless otherwise specified | 9 Months Ended
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Sep. 30, 2014
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of period | $ 4,958 | [1],[2]
Accretion expense | 164 | [3]
Liabilities settled | (56) |
Liabilities incurred in the current year | 3,433 | [4]
Balance at end of period | 8,499 |
Duke Energy Carolinas [Member] |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of period | 1,594 |
Accretion expense | 71 | [3]
Liabilities settled |  |
Liabilities incurred in the current year | 2,026 | [4]
Balance at end of period | 3,691 |
Progress Energy [Member] |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of period | 2,570 | [2]
Accretion expense | 91 | [3]
Liabilities settled | (52) |
Liabilities incurred in the current year | 1,406 | [4]
Balance at end of period | 4,015 |
Duke Energy Progress [Member] |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of period | 1,737 | [2]
Accretion expense | 63 | [3]
Liabilities settled |  |
Liabilities incurred in the current year | 1,406 | [4]
Balance at end of period | 3,206 |
Asset retirement obligation, current | $ 8 |
[1] | The balance as of December 31, 2013 primarily relates to decommissioning nuclear power facilities, asbestos removal and closure of landfills at fossil generation facilities.
[2] | The balance at December 31, 2013 includes $8 million reported in Other current liabilities on the Condensed Consolidated Balance Sheets at Duke Energy, Progress Energy and Duke Energy Progress.
[3] | Substantially all accretion expense for the nine months ended September 30, 2014 relates to Duke Energy's regulated electric operations from previously established asset retirement obligations and has been deferred in accordance with regulatory accounting treatment.
[4] | Amounts relate to asset obligations recorded in the third quarter of 2014 as a result of the Coal Ash Act and an agreement with the SCDHEC related to the W.S Lee Steam Station.

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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Asset Retirement Obligation -URI http://asc.fasb.org/extlink&oid=6505190 + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Current portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of asset retirement obligations incurred during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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