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Fair Value Of Financial Assets And Liabilities (Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended |  |  |  |  | 3 Months Ended
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Mar. 31, 2013 | Mar. 31, 2012 | Mar. 31, 2013 Available For Sale Auction Rate Securities [Member] | Mar. 31, 2012 Available For Sale Auction Rate Securities [Member] | Mar. 31, 2013 Available For Sale Ndtf Investments [Member] | Mar. 31, 2012 Available For Sale Ndtf Investments [Member] | Mar. 31, 2013 Derivative [Member] | Mar. 31, 2012 Derivative [Member] | Mar. 31, 2013 Duke Energy Carolinas [Member] | Mar. 31, 2012 Duke Energy Carolinas [Member] | Mar. 31, 2013 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member] | Dec. 31, 2012 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member] | Mar. 31, 2012 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member] | Dec. 31, 2011 Duke Energy Carolinas [Member] Available For Sale Auction Rate Securities [Member] | Mar. 31, 2013 Duke Energy Carolinas [Member] Available For Sale Ndtf Investments [Member] | Mar. 31, 2012 Duke Energy Carolinas [Member] Available For Sale Ndtf Investments [Member] | Mar. 31, 2013 Duke Energy Carolinas [Member] Derivative [Member] | Mar. 31, 2013 Progress Energy [Member] | Mar. 31, 2012 Progress Energy [Member] | Mar. 31, 2013 Duke Energy Progress [Member] | Mar. 31, 2012 Duke Energy Progress [Member] | Mar. 31, 2013 Duke Energy Ohio [Member] | Mar. 31, 2012 Duke Energy Ohio [Member] | Mar. 31, 2013 Duke Energy Indiana [Member] | Mar. 31, 2012 Duke Energy Indiana [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance | $ 13 | $ 85 | $ 29 | $ 71 | $ 69 | $ 53 | $ (85) | $ (39) | $ 60 | $ 65 | $ 3 | $ 3 | $ 12 | $ 12 | $ 69 | $ 53 | $ (12) | $ (38) | $ (24) | $ (38) | $ (24) | $ (6) | $ (3) | $ 10 | $ 4
Revenue, regulated electric | (6) | 8 |  |  |  |  | (6) | 8 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (5) | 8
Revenue, non-regulated electric, natural gas | (4) | (2) |  |  |  |  | (4) | (2) |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 |  |  |
Gains on available for sale securities and other | (1) | 1 | (1) | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchases |  | 2 |  |  |  | 2 |  |  |  | 2 |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |
Issuances | 6 |  |  |  |  |  | 6 |  |  |  |  |  |  |  |  |  |  | 6 |  | 6 |  |  |  |  |
Settlements | 7 | (9) |  |  |  |  | 7 | (9) | 7 |  |  |  |  |  |  |  | 7 |  |  |  |  | (3) |  |  | (10)
Total gains (losses) included on the Condensed Consolidated Balance Sheet as regulatory asset or liability | 1 | 1 |  |  | 1 | 1 |  |  | 1 | 1 |  |  |  |  | 1 | 1 |  | 1 | (3) | 1 | (3) |  | (1) | (1) | 1
Ending balance | 16 | 86 | 28 | 72 | 70 | 56 | (82) | (42) | 68 | 68 | 3 | 3 | 12 | 12 | 70 | 56 | (5) | (31) | (27) | (31) | (27) | (5) | (4) | 4 | 3
Revenue, regulated electric | 1 |  |  |  |  |  | 1 |  | (5) |  |  |  |  |  |  |  | (5) | 6 |  | 6 |  |  |  |  |
Revenue, non regulated electric and other - non-regulated | (10) |  |  |  |  |  | (10) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (2) | 1 |  |
Total | $ (9) |  |  |  |  |  | $ (9) |  | $ (5) |  |  |  |  |  |  |  | $ (5) | $ 6 |  | $ 6 |  | $ (2) | $ 1 |  |

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- Definition Revenue where unrealized (holding) gain (loss) is reported in the statement of income (or activities) relating to those assets, liabilities, and financial instruments classified in shareholders' equity still held for which fair value is measured on a recurring basis using significant unobservable inputs (level 3). + References No definition available. + Details
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- Definition This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in regulated earnings or resulted in a change in net asset value. + References No definition available. + Details
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- Definition Regulated Revenue where unrealized (holding) gain (loss) is reported in the statement to those assets, liabilitiesn and financials instruments classified in shareholders' equity still held for which fair value is measured on a recurring basis using significant unobserveable inputs (level 3). + References No definition available. + Details
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- Definition This element represents deferred gains or losses as regulatory assets and liabilities [net] measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. + References No definition available. + Details
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- Details
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- Definition Amount of realized and unrealized gain (loss) included in earnings, which have arisen from the use of significant unobservable inputs (level 3) to measure fair value of assets, liabilities, and financial instruments classified in shareholders' equity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -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. + Details
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- Definition Issues that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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