v3.3.0.814

Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions | Sep. 30, 2015 | Dec. 31, 2014
--- | --- | ---
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | $ 1,724 | $ 2,004
Gross Unrealized Holding Losses | 89 | 38
Estimated Fair Value | 5,976 | 5,901
Ndtf [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1,692 | 1,965
Gross Unrealized Holding Losses | 84 | 35
Estimated Fair Value | 5,562 | 5,549
Ndtf [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 156 | 136
Ndtf [Member] | Equity Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1,655 | 1,926
Gross Unrealized Holding Losses | 71 | 29
Estimated Fair Value | 3,396 | 3,650
Ndtf [Member] | Corporate Debt Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 9 | 14
Gross Unrealized Holding Losses | 7 | 2
Estimated Fair Value | 500 | 454
Ndtf [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 4 | 5
Gross Unrealized Holding Losses | 2 |
Estimated Fair Value | 207 | 184
Ndtf [Member] | US Treasury and Government [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 23 | 19
Gross Unrealized Holding Losses | 1 | 2
Estimated Fair Value | 1,131 | 978
Ndtf [Member] | Other Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1 | 1
Gross Unrealized Holding Losses | 3 | 2
Estimated Fair Value | 172 | 147
Other Classification [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 32 | 39
Gross Unrealized Holding Losses | 5 | 3
Estimated Fair Value | 414 | 352
Other Classification [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 32 | 15
Other Classification [Member] | Equity Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 27 | 34
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 90 | 96
Other Classification [Member] | Corporate Debt Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1 | 1
Gross Unrealized Holding Losses | 2 | 1
Estimated Fair Value | 98 | 58
Other Classification [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 3
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | 73 | 76
Other Classification [Member] | US Treasury and Government [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1 |
Estimated Fair Value | 52 | 27
Other Classification [Member] | Other Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains |  | 1
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | 69 | 80
Duke Energy Carolinas [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 943 | 1,119
Gross Unrealized Holding Losses | 54 | 23
Estimated Fair Value | 2,953 | 3,035
Duke Energy Carolinas [Member] | Ndtf [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 943 | 1,119
Gross Unrealized Holding Losses | 53 | 22
Estimated Fair Value | 2,950 | 3,032
Duke Energy Carolinas [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 25 | 51
Duke Energy Carolinas [Member] | Ndtf [Member] | Equity Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 930 | 1,102
Gross Unrealized Holding Losses | 42 | 17
Estimated Fair Value | 1,990 | 2,162
Duke Energy Carolinas [Member] | Ndtf [Member] | Corporate Debt Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 5 | 8
Gross Unrealized Holding Losses | 6 | 2
Estimated Fair Value | 342 | 316
Duke Energy Carolinas [Member] | Ndtf [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1 | 1
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 69 | 62
Duke Energy Carolinas [Member] | Ndtf [Member] | US Treasury and Government [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 6 | 7
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | 383 | 308
Duke Energy Carolinas [Member] | Ndtf [Member] | Other Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1 | 1
Gross Unrealized Holding Losses | 3 | 2
Estimated Fair Value | 141 | 133
Duke Energy Carolinas [Member] | Other Classification [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | 3 | 3
Duke Energy Carolinas [Member] | Other Classification [Member] | Other Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | 3 | 3
Progress Energy [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 752 | 849
Gross Unrealized Holding Losses | 31 | 13
Estimated Fair Value | 2,678 | 2,575
Progress Energy [Member] | Ndtf [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 749 | 846
Gross Unrealized Holding Losses | 31 | 13
Estimated Fair Value | 2,612 | 2,517
Progress Energy [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 131 | 85
Progress Energy [Member] | Ndtf [Member] | Equity Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 725 | 824
Gross Unrealized Holding Losses | 29 | 12
Estimated Fair Value | 1,406 | 1,488
Progress Energy [Member] | Ndtf [Member] | Corporate Debt Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 4 | 6
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 158 | 138
Progress Energy [Member] | Ndtf [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 4
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 138 | 122
Progress Energy [Member] | Ndtf [Member] | US Treasury and Government [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 17 | 12
Gross Unrealized Holding Losses |  | 1
Estimated Fair Value | 748 | 670
Progress Energy [Member] | Ndtf [Member] | Other Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 31 | 14
Progress Energy [Member] | Other Classification [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 3
Estimated Fair Value | 66 | 58
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 23 | 15
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 3
Estimated Fair Value | 43 | 43
Duke Energy Progress [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 553 | 630
Gross Unrealized Holding Losses | 25 | 11
Estimated Fair Value | 1,944 | 1,711
Duke Energy Progress [Member] | Ndtf [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 553 | 630
Gross Unrealized Holding Losses | 25 | 11
Estimated Fair Value | 1,943 | 1,711
Duke Energy Progress [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 87 | 50
Duke Energy Progress [Member] | Ndtf [Member] | Equity Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 535 | 612
Gross Unrealized Holding Losses | 23 | 10
Estimated Fair Value | 1,107 | 1,171
Duke Energy Progress [Member] | Ndtf [Member] | Corporate Debt Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 5
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 109 | 97
Duke Energy Progress [Member] | Ndtf [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 4
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 136 | 120
Duke Energy Progress [Member] | Ndtf [Member] | US Treasury and Government [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 12 | 9
Gross Unrealized Holding Losses |  | 1
Estimated Fair Value | 485 | 265
Duke Energy Progress [Member] | Ndtf [Member] | Other Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 19 | 8
Duke Energy Progress [Member] | Other Classification [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 1 |
Duke Energy Progress [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 1 |
Duke Energy Florida [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 199 | 219
Gross Unrealized Holding Losses | 6 | 2
Estimated Fair Value | 723 | 850
Duke Energy Florida [Member] | Ndtf [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 196 | 216
Gross Unrealized Holding Losses | 6 | 2
Estimated Fair Value | 669 | 806
Duke Energy Florida [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 44 | 35
Duke Energy Florida [Member] | Ndtf [Member] | Equity Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 190 | 212
Gross Unrealized Holding Losses | 6 | 2
Estimated Fair Value | 299 | 317
Duke Energy Florida [Member] | Ndtf [Member] | Corporate Debt Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 1 | 1
Estimated Fair Value | 49 | 41
Duke Energy Florida [Member] | Ndtf [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 2 | 2
Duke Energy Florida [Member] | Ndtf [Member] | US Treasury and Government [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 5 | 3
Estimated Fair Value | 263 | 405
Duke Energy Florida [Member] | Ndtf [Member] | Other Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 12 | 6
Duke Energy Florida [Member] | Other Classification [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 3
Estimated Fair Value | 54 | 44
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 11 | 1
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 3 | 3
Estimated Fair Value | 43 | 43
Duke Energy Indiana [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 23 | 28
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | 97 | 101
Duke Energy Indiana [Member] | Other Classification [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 23 | 28
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | 97 | 101
Duke Energy Indiana [Member] | Other Classification [Member] | Equity Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Gains | 23 | 28
Estimated Fair Value | 67 | 71
Duke Energy Indiana [Member] | Other Classification [Member] | Corporate Debt Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 3 |
Duke Energy Indiana [Member] | Other Classification [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Gross Unrealized Holding Losses | 1 | 1
Estimated Fair Value | $ 27 | $ 30

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