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Investments in Debt and Equity Securities (Estimated Fair Value of Investments in Debt and Equity Securities) (Details) - USD ($) $ in Millions | Mar. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Debt Securities, Available-for-sale |  |
Estimated Fair Value | $ 3,133 |
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 4,539 | $ 5,033
Unrealized Holding Losses | 202 | 66
Estimated Fair Value | 10,371 | 10,893
Duke Energy Carolinas |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,419 |
Progress Energy |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,452 |
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 1,866 | 2,062
Unrealized Holding Losses | 92 | 36
Estimated Fair Value | 4,428 | 4,688
Duke Energy Progress |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,031 |
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 1,768 | 1,957
Unrealized Holding Losses | 74 | 29
Estimated Fair Value | 3,885 | 4,105
Duke Energy Florida |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 421 |
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 98 | 105
Unrealized Holding Losses | 18 | 7
Estimated Fair Value | 542 | 582
Duke Energy Indiana |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 63 |
NDTF |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 128 | 160
Equity Securities, FV-NI |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain | 4,486 | 4,905
Equity Securities, FV-NI, Accumulated Unrealized Loss | 62 | 43
Equity securities, FV-NI | 6,853 | 7,350
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 2,845 | 2,891
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 4,507 | 4,992
Unrealized Holding Losses | 185 | 63
Estimated Fair Value | 9,826 | 10,401
NDTF | Duke Energy Carolinas |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 60 | 53
Equity Securities, FV-NI |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain | 2,632 | 2,887
Equity Securities, FV-NI, Accumulated Unrealized Loss | 30 | 19
Equity securities, FV-NI | 3,962 | 4,265
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,419 | 1,441
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 2,642 | 2,932
Unrealized Holding Losses | 93 | 27
Estimated Fair Value | 5,441 | 5,759
NDTF | Progress Energy |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 68 | 107
Equity Securities, FV-NI |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain | 1,854 | 2,018
Equity Securities, FV-NI, Accumulated Unrealized Loss | 32 | 24
Equity securities, FV-NI | 2,891 | 3,085
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,426 | 1,450
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 1,865 | 2,060
Unrealized Holding Losses | 92 | 36
Estimated Fair Value | 4,385 | 4,642
NDTF | Duke Energy Progress |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 58 | 94
Equity Securities, FV-NI |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain | 1,757 | 1,915
Equity Securities, FV-NI, Accumulated Unrealized Loss | 32 | 23
Equity securities, FV-NI | 2,782 | 2,970
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 1,031 | 1,025
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 1,768 | 1,957
Unrealized Holding Losses | 74 | 29
Estimated Fair Value | 3,871 | 4,089
NDTF | Duke Energy Florida |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 10 | 13
Equity Securities, FV-NI |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain | 97 | 103
Equity Securities, FV-NI, Accumulated Unrealized Loss |  | 1
Equity securities, FV-NI | 109 | 115
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 395 | 425
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 97 | 103
Unrealized Holding Losses | 18 | 7
Estimated Fair Value | 514 | 553
Other Investments |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 110 | 36
Equity Securities, FV-NI |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain | 31 | 36
Equity Securities, FV-NI, Accumulated Unrealized Loss | 4 |
Equity securities, FV-NI | 147 | 156
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 288 | 300
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 32 | 41
Unrealized Holding Losses | 17 | 3
Estimated Fair Value | 545 | 492
Other Investments | Progress Energy |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 17 | 20
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 26 | 26
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 1 | 2
Estimated Fair Value | 43 | 46
Other Investments | Duke Energy Progress |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 14 | 16
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Estimated Fair Value | 14 | 16
Other Investments | Duke Energy Florida |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 2 | 3
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 26 | 26
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 1 | 2
Estimated Fair Value | 28 | 29
Other Investments | Duke Energy Indiana |  |
Available-for-sale Securities |  |
Cash and cash equivalents | 1 |
Equity Securities, FV-NI |  |
Equity Securities, FV-NI, Accumulated Unrealized Gain | 4 | 6
Equity Securities, FV-NI, Accumulated Unrealized Loss | 4 |
Equity securities, FV-NI | 91 | 97
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 63 | 64
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract] |  |
Unrealized Holding Gains | 4 | 7
Unrealized Holding Losses | 6 | 1
Estimated Fair Value | 155 | 161
Corporate debt securities | NDTF |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 9 | 39
Gross Unrealized Holding Losses | 43 | 6
Estimated Fair Value | 786 | 829
Corporate debt securities | NDTF | Duke Energy Carolinas |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 6 | 24
Gross Unrealized Holding Losses | 30 | 4
Estimated Fair Value | 503 | 506
Corporate debt securities | NDTF | Progress Energy |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 3 | 15
Gross Unrealized Holding Losses | 13 | 2
Estimated Fair Value | 283 | 323
Corporate debt securities | NDTF | Duke Energy Progress |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 3 | 15
Gross Unrealized Holding Losses | 12 | 2
Estimated Fair Value | 255 | 282
Corporate debt securities | NDTF | Duke Energy Florida |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Losses | 1 |
Estimated Fair Value | 28 | 41
Corporate debt securities | Other Investments |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains |  | 2
Gross Unrealized Holding Losses | 7 | 1
Estimated Fair Value | 124 | 119
Corporate debt securities | Other Investments | Duke Energy Indiana |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 8 | 6
Municipal bonds | NDTF |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 2 | 14
Gross Unrealized Holding Losses | 16 | 1
Estimated Fair Value | 321 | 314
Municipal bonds | NDTF | Duke Energy Carolinas |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains |  | 2
Gross Unrealized Holding Losses | 5 |
Estimated Fair Value | 52 | 48
Municipal bonds | NDTF | Progress Energy |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 2 | 12
Gross Unrealized Holding Losses | 11 | 1
Estimated Fair Value | 269 | 266
Municipal bonds | NDTF | Duke Energy Progress |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 2 | 12
Gross Unrealized Holding Losses | 11 | 1
Estimated Fair Value | 269 | 266
Municipal bonds | Other Investments |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 1 | 3
Gross Unrealized Holding Losses | 2 | 1
Estimated Fair Value | 83 | 80
Municipal bonds | Other Investments | Progress Energy |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 1 | 2
Estimated Fair Value | 26 | 26
Municipal bonds | Other Investments | Duke Energy Florida |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 1 | 2
Estimated Fair Value | 26 | 26
Municipal bonds | Other Investments | Duke Energy Indiana |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains |  | 1
Gross Unrealized Holding Losses | 2 | 1
Estimated Fair Value | 49 | 46
U.S. government bonds | NDTF |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 10 | 31
Gross Unrealized Holding Losses | 57 | 12
Estimated Fair Value | 1,561 | 1,568
U.S. government bonds | NDTF | Duke Energy Carolinas |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 4 | 16
Gross Unrealized Holding Losses | 21 | 3
Estimated Fair Value | 692 | 712
U.S. government bonds | NDTF | Progress Energy |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 6 | 15
Gross Unrealized Holding Losses | 36 | 9
Estimated Fair Value | 869 | 856
U.S. government bonds | NDTF | Duke Energy Progress |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains | 6 | 15
Gross Unrealized Holding Losses | 19 | 3
Estimated Fair Value | 502 | 472
U.S. government bonds | NDTF | Duke Energy Florida |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Losses | 17 | 6
Estimated Fair Value | 367 | 384
U.S. government bonds | Other Investments |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Losses | 2 |
Estimated Fair Value | 45 | 56
U.S. government bonds | Other Investments | Duke Energy Indiana |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 6 | 12
Other debt securities | NDTF |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains |  | 3
Gross Unrealized Holding Losses | 7 | 1
Estimated Fair Value | 177 | 180
Other debt securities | NDTF | Duke Energy Carolinas |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Gains |  | 3
Gross Unrealized Holding Losses | 7 | 1
Estimated Fair Value | 172 | 175
Other debt securities | NDTF | Progress Energy |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 5 | 5
Other debt securities | NDTF | Duke Energy Progress |  |
Debt Securities, Available-for-sale |  |
Estimated Fair Value | 5 | 5
Other debt securities | Other Investments |  |
Debt Securities, Available-for-sale |  |
Gross Unrealized Holding Losses | 2 | 1
Estimated Fair Value | $ 36 | $ 45

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