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Investments in Debt and Equity Securities (Estimated Fair Value of Investments in Debt and Equity Securities) (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Debt Securities, Available-for-sale |  |
Estimated Fair Value | $ 3,191 |
Total Investments |  |
Unrealized Holding Gains | 5,033 | $ 4,387
Unrealized Holding Losses | 66 | 55
Estimated Fair Value | 10,893 | 9,687
NDTF |  |
Equity Securities, FV-NI |  |
Gross Unrealized Holding Gains | 4,905 | 4,138
Gross Unrealized Holding Losses | 43 | 54
Estimated Fair Value | 7,350 | 6,235
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 2,891 | 2,717
Total Investments |  |
Unrealized Holding Gains | 4,992 | 4,295
Unrealized Holding Losses | 63 | 55
Estimated Fair Value | 10,401 | 9,129
NDTF | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 160 | 177
NDTF | Corporate debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 39 | 76
Gross Unrealized Holding Losses | 6 | 1
Estimated Fair Value | 829 | 806
NDTF | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 14 | 22
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 314 | 370
NDTF | U.S. government bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 31 | 51
Gross Unrealized Holding Losses | 12 |
Estimated Fair Value | 1,568 | 1,361
NDTF | Other debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 3 | 8
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 180 | 180
Other Investments |  |
Equity Securities, FV-NI |  |
Gross Unrealized Holding Gains | 36 | 79
Estimated Fair Value | 156 | 146
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 300 | 285
Total Investments |  |
Unrealized Holding Gains | 41 | 92
Unrealized Holding Losses | 3 |
Estimated Fair Value | 492 | 558
Other Investments | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 36 | 127
Other Investments | Corporate debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 2 | 8
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 119 | 110
Other Investments | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 3 | 5
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 80 | 86
Other Investments | U.S. government bonds |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 56 | 42
Other Investments | Other debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 45 | 47
Duke Energy Carolinas |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,441 |
Duke Energy Carolinas | NDTF |  |
Equity Securities, FV-NI |  |
Gross Unrealized Holding Gains | 2,887 | 2,442
Gross Unrealized Holding Losses | 19 | 23
Estimated Fair Value | 4,265 | 3,685
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,441 | 1,250
Total Investments |  |
Unrealized Holding Gains | 2,932 | 2,529
Unrealized Holding Losses | 27 | 24
Estimated Fair Value | 5,759 | 4,965
Duke Energy Carolinas | NDTF | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 53 | 30
Duke Energy Carolinas | NDTF | Corporate debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 24 | 49
Gross Unrealized Holding Losses | 4 | 1
Estimated Fair Value | 506 | 510
Duke Energy Carolinas | NDTF | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 2 | 6
Estimated Fair Value | 48 | 91
Duke Energy Carolinas | NDTF | U.S. government bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 16 | 25
Gross Unrealized Holding Losses | 3 |
Estimated Fair Value | 712 | 475
Duke Energy Carolinas | NDTF | Other debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 3 | 7
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 175 | 174
Progress Energy |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,476 |
Total Investments |  |
Unrealized Holding Gains | 2,062 | 1,769
Unrealized Holding Losses | 36 | 31
Estimated Fair Value | 4,688 | 4,296
Progress Energy | NDTF |  |
Equity Securities, FV-NI |  |
Gross Unrealized Holding Gains | 2,018 | 1,696
Gross Unrealized Holding Losses | 24 | 31
Estimated Fair Value | 3,085 | 2,550
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,450 | 1,467
Total Investments |  |
Unrealized Holding Gains | 2,060 | 1,766
Unrealized Holding Losses | 36 | 31
Estimated Fair Value | 4,642 | 4,164
Progress Energy | NDTF | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 107 | 147
Progress Energy | NDTF | Corporate debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 15 | 27
Gross Unrealized Holding Losses | 2 |
Estimated Fair Value | 323 | 296
Progress Energy | NDTF | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 12 | 16
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 266 | 279
Progress Energy | NDTF | U.S. government bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 15 | 26
Gross Unrealized Holding Losses | 9 |
Estimated Fair Value | 856 | 886
Progress Energy | NDTF | Other debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains |  | 1
Estimated Fair Value | 5 | 6
Progress Energy | Other Investments |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 26 | 26
Total Investments |  |
Unrealized Holding Gains | 2 | 3
Estimated Fair Value | 46 | 132
Progress Energy | Other Investments | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 20 | 106
Progress Energy | Other Investments | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 2 | 3
Estimated Fair Value | 26 | 26
Duke Energy Progress |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,025 |
Total Investments |  |
Unrealized Holding Gains | 1,957 | 1,687
Unrealized Holding Losses | 29 | 31
Estimated Fair Value | 4,105 | 3,529
Duke Energy Progress | NDTF |  |
Equity Securities, FV-NI |  |
Gross Unrealized Holding Gains | 1,915 | 1,617
Gross Unrealized Holding Losses | 23 | 31
Estimated Fair Value | 2,970 | 2,459
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,025 | 993
Total Investments |  |
Unrealized Holding Gains | 1,957 | 1,687
Unrealized Holding Losses | 29 | 31
Estimated Fair Value | 4,089 | 3,528
Duke Energy Progress | NDTF | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 94 | 76
Duke Energy Progress | NDTF | Corporate debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 15 | 27
Gross Unrealized Holding Losses | 2 |
Estimated Fair Value | 282 | 296
Duke Energy Progress | NDTF | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 12 | 16
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 266 | 279
Duke Energy Progress | NDTF | U.S. government bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 15 | 26
Gross Unrealized Holding Losses | 3 |
Estimated Fair Value | 472 | 412
Duke Energy Progress | NDTF | Other debt securities |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains |  | 1
Estimated Fair Value | 5 | 6
Duke Energy Progress | Other Investments |  |
Total Investments |  |
Estimated Fair Value | 16 | 1
Duke Energy Progress | Other Investments | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 16 | 1
Duke Energy Florida |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 451 |
Total Investments |  |
Unrealized Holding Gains | 105 | 82
Unrealized Holding Losses | 7 |
Estimated Fair Value | 582 | 663
Duke Energy Florida | NDTF |  |
Equity Securities, FV-NI |  |
Gross Unrealized Holding Gains | 103 | 79
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 115 | 91
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 425 | 474
Total Investments |  |
Unrealized Holding Gains | 103 | 79
Unrealized Holding Losses | 7 |
Estimated Fair Value | 553 | 636
Duke Energy Florida | NDTF | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 13 | 71
Duke Energy Florida | NDTF | Corporate debt securities |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 41 |
Duke Energy Florida | NDTF | U.S. government bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Losses | 6 |
Estimated Fair Value | 384 | 474
Duke Energy Florida | Other Investments |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 26 | 26
Total Investments |  |
Unrealized Holding Gains | 2 | 3
Estimated Fair Value | 29 | 27
Duke Energy Florida | Other Investments | Cash and cash equivalents |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 3 | 1
Duke Energy Florida | Other Investments | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 2 | 3
Estimated Fair Value | 26 | 26
Duke Energy Indiana |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 64 |
Total Investments |  |
Unrealized Holding Gains | 7 | 59
Unrealized Holding Losses | 1 |
Estimated Fair Value | 161 | 143
Duke Energy Indiana | Other Investments |  |
Available-for-sale Securities |  |
Cash and cash equivalents |  | 1
Equity Securities, FV-NI |  |
Gross Unrealized Holding Gains | 6 | 58
Estimated Fair Value | 97 | 97
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 64 | 45
Duke Energy Indiana | Other Investments | Corporate debt securities |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 6 | 3
Duke Energy Indiana | Other Investments | Municipal bonds |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 1 | 1
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 46 | 38
Duke Energy Indiana | Other Investments | U.S. government bonds |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | $ 12 | $ 4

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