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Investments in Debt and Equity Securities (Equity Securities, FV-NI - ASU 2016-01) (Details) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 USD ($) | Sep. 30, 2018 USD ($)
Equity Securities, FV-NI, Realized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, realized gain | $ 19 | $ 85
Equity securities, FV-NI, realized loss | 16 | 60
Ndtf [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, unrealized gain | 3,117 | 3,117
Equity securities, FV-NI, unrealized loss | 48 | 48
Equity securities, FV-NI | 5,272 | 5,272
Other Classification [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, unrealized gain | 51 | 51
Equity securities, FV-NI | 115 | 115
Duke Energy Carolinas [Member] |  |
Equity Securities, FV-NI, Realized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, realized gain | 11 | 47
Equity securities, FV-NI, realized loss | 8 | 30
Duke Energy Carolinas [Member] | Ndtf [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, unrealized gain | 1,692 | 1,692
Equity securities, FV-NI, unrealized loss | 29 | 29
Equity securities, FV-NI | 2,890 | 2,890
Progress Energy [Member] |  |
Equity Securities, FV-NI, Realized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, realized gain | 8 | 38
Equity securities, FV-NI, realized loss | 8 | 30
Progress Energy [Member] | Ndtf [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, unrealized gain | 1,425 | 1,425
Equity securities, FV-NI, unrealized loss | 19 | 19
Equity securities, FV-NI | 2,382 | 2,382
Duke Energy Progress [Member] |  |
Equity Securities, FV-NI, Realized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, realized gain | 7 | 32
Equity securities, FV-NI, realized loss | 7 | 27
Duke Energy Progress [Member] | Ndtf [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, unrealized gain | 1,101 | 1,101
Equity securities, FV-NI, unrealized loss | 14 | 14
Equity securities, FV-NI | 1,913 | 1,913
Duke Energy Florida [Member] |  |
Equity Securities, FV-NI, Realized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, realized gain | 1 | 6
Equity securities, FV-NI, realized loss | 1 | 3
Duke Energy Florida [Member] | Ndtf [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, unrealized gain | 324 | 324
Equity securities, FV-NI, unrealized loss | 5 | 5
Equity securities, FV-NI | 469 | 469
Duke Energy Indiana [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI, unrealized gain | 40 | 40
Equity securities, FV-NI | 78 | 78
Duke Energy Indiana [Member] | Other Classification [Member] |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain (Loss) [Abstract] |  |
Equity securities, FV-NI | $ 78 | $ 78

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- Definition Amount of accumulated unrealized gain on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Substantially all of the associated unrealized gains and losses on these investments are deferred as a regulatory asset or liability. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Substantially all of the associated unrealized gains and losses on these investments are deferred as a regulatory asset or liability. + References No definition available. + Details
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- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740 + Details
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