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Investments in Debt and Equity Securities (Tables) | 12 Months Ended
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Dec. 31, 2020
Investment [Line Items] |
Summary of Investments in Debt and Equity Securities | The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.
| December 31, 2020 |  | December 31, 2019
| Gross |  | Gross |  |  |  | Gross |  | Gross |  |
| Unrealized |  | Unrealized |  |  |  | Unrealized |  | Unrealized |  |
| Holding |  | Holding |  | Estimated |  | Holding |  | Holding |  | Estimated
(in millions) | Gains |  | Losses |  | Fair Value |  | Gains |  | Losses |  | Fair Value
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 177 |  |  | $ | — |  |  | $ | — |  |  | $ | 101 |
Equity securities | 4,138 |  |  | 54 |  |  | 6,235 |  |  | 3,523 |  |  | 55 |  |  | 5,661 |
Corporate debt securities | 76 |  |  | 1 |  |  | 806 |  |  | 37 |  |  | 1 |  |  | 603 |
Municipal bonds | 22 |  |  | — |  |  | 370 |  |  | 13 |  |  | — |  |  | 368 |
U.S. government bonds | 51 |  |  | — |  |  | 1,361 |  |  | 33 |  |  | 1 |  |  | 1,256 |
Other debt securities | 8 |  |  | — |  |  | 180 |  |  | 3 |  |  | — |  |  | 141 |
Total NDTF Investments | $ | 4,295 |  |  | $ | 55 |  |  | $ | 9,129 |  |  | $ | 3,609 |  |  | $ | 57 |  |  | $ | 8,130 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 127 |  |  | $ | — |  |  | $ | — |  |  | $ | 52 |
Equity securities | 79 |  |  | — |  |  | 146 |  |  | 57 |  |  | — |  |  | 122 |
Corporate debt securities | 8 |  |  | — |  |  | 110 |  |  | 3 |  |  | — |  |  | 67 |
Municipal bonds | 5 |  |  | — |  |  | 86 |  |  | 4 |  |  | — |  |  | 94 |
U.S. government bonds | — |  |  | — |  |  | 42 |  |  | 2 |  |  | — |  |  | 41 |
Other debt securities | — |  |  | — |  |  | 47 |  |  | — |  |  | — |  |  | 56 |
Total Other Investments | $ | 92 |  |  | $ | — |  |  | $ | 558 |  |  | $ | 66 |  |  | $ | — |  |  | $ | 432 |
Total Investments | $ | 4,387 |  |  | $ | 55 |  |  | $ | 9,687 |  |  | $ | 3,675 |  |  | $ | 57 |  |  | $ | 8,562 |
Investments Classified by Contractual Maturity Date | The table below summarizes the maturity date for debt securities.
(in millions) | December 31, 2020
Due in one year or less | $ | 149 |
Due after one through five years | 922 |
Due after five through 10 years | 671 |
Due after 10 years | 1,260 |
Total | $ | 3,002 |
Schedule of Realized Gain (Loss) | Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the years ended December 31, 2020, 2019 and 2018, were as follows.
| Years Ended December 31,
(in millions) | 2020 |  | 2019 |  | 2018
FV-NI: |  |  |  |  |
Realized gains | $ | 366 |  |  | $ | 172 |  |  | $ | 168 |
Realized losses | 174 |  |  | 151 |  |  | 126 |
AFS: |  |  |  |  |
Realized gains | 96 |  |  | 94 |  |  | 22 |
Realized losses | 51 |  |  | 67 |  |  | 51 |
Duke Energy Carolinas |
Investment [Line Items] |
Summary of Investments in Debt and Equity Securities | The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.
| December 31, 2020 |  | December 31, 2019
| Gross |  | Gross |  |  |  | Gross |  | Gross |  |
| Unrealized |  | Unrealized |  |  |  | Unrealized |  | Unrealized |  |
| Holding |  | Holding |  | Estimated |  | Holding |  | Holding |  | Estimated
(in millions) | Gains |  | Losses |  | Fair Value |  | Gains |  | Losses |  | Fair Value
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 30 |  |  | $ | — |  |  | $ | — |  |  | $ | 21 |
Equity securities | 2,442 |  |  | 23 |  |  | 3,685 |  |  | 1,914 |  |  | 8 |  |  | 3,154 |
Corporate debt securities | 49 |  |  | 1 |  |  | 510 |  |  | 21 |  |  | 1 |  |  | 361 |
Municipal bonds | 6 |  |  | — |  |  | 91 |  |  | 3 |  |  | — |  |  | 96 |
U.S. government bonds | 25 |  |  | — |  |  | 475 |  |  | 16 |  |  | 1 |  |  | 578 |
Other debt securities | 7 |  |  | — |  |  | 174 |  |  | 3 |  |  | — |  |  | 137 |
Total NDTF Investments | $ | 2,529 |  |  | $ | 24 |  |  | $ | 4,965 |  |  | $ | 1,957 |  |  | $ | 10 |  |  | $ | 4,347 |
Investments Classified by Contractual Maturity Date | The table below summarizes the maturity date for debt securities.
(in millions) | December 31, 2020
Due in one year or less | $ | 14 |
Due after one through five years | 299 |
Due after five through 10 years | 279 |
Due after 10 years | 658 |
Total | $ | 1,250 |
Schedule of Realized Gain (Loss) | Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the years ended December 31, 2020, 2019 and 2018, were as follows.
| Years Ended December 31,
(in millions) | 2020 |  | 2019 |  | 2018
FV-NI: |  |  |  |  |
Realized gains | $ | 64 |  |  | $ | 113 |  |  | $ | 89 |
Realized losses | 99 |  |  | 107 |  |  | 73 |
AFS: |  |  |  |  |
Realized gains | 60 |  |  | 55 |  |  | 19 |
Realized losses | 37 |  |  | 38 |  |  | 35 |
Progress Energy |
Investment [Line Items] |
Summary of Investments in Debt and Equity Securities | The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.
| December 31, 2020 |  | December 31, 2019
| Gross |  | Gross |  |  |  | Gross |  | Gross |  |
| Unrealized |  | Unrealized |  |  |  | Unrealized |  | Unrealized |  |
| Holding |  | Holding |  | Estimated |  | Holding |  | Holding |  | Estimated
(in millions) | Gains |  | Losses |  | Fair Value |  | Gains |  | Losses |  | Fair Value
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 147 |  |  | $ | — |  |  | $ | — |  |  | $ | 80 |
Equity securities | 1,696 |  |  | 31 |  |  | 2,550 |  |  | 1,609 |  |  | 47 |  |  | 2,507 |
Corporate debt securities | 27 |  |  | — |  |  | 296 |  |  | 16 |  |  | — |  |  | 242 |
Municipal bonds | 16 |  |  | — |  |  | 279 |  |  | 10 |  |  | — |  |  | 272 |
U.S. government bonds | 26 |  |  | — |  |  | 886 |  |  | 17 |  |  | — |  |  | 678 |
Other debt securities | 1 |  |  | — |  |  | 6 |  |  | — |  |  | — |  |  | 4 |
Total NDTF Investments | $ | 1,766 |  |  | $ | 31 |  |  | $ | 4,164 |  |  | $ | 1,652 |  |  | $ | 47 |  |  | $ | 3,783 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 106 |  |  | $ | — |  |  | $ | — |  |  | $ | 49 |
Municipal bonds | 3 |  |  | — |  |  | 26 |  |  | 3 |  |  | — |  |  | 51 |
Total Other Investments | $ | 3 |  |  | $ | — |  |  | $ | 132 |  |  | $ | 3 |  |  | $ | — |  |  | $ | 100 |
Total Investments | $ | 1,769 |  |  | $ | 31 |  |  | $ | 4,296 |  |  | $ | 1,655 |  |  | $ | 47 |  |  | $ | 3,883 |
Investments Classified by Contractual Maturity Date | The table below summarizes the maturity date for debt securities.
(in millions) | December 31, 2020
Due in one year or less | $ | 109 |
Due after one through five years | 567 |
Due after five through 10 years | 298 |
Due after 10 years | 519 |
Total | $ | 1,493 |
Schedule of Realized Gain (Loss) | Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the years ended December 31, 2020, 2019 and 2018, were as follows.
| Years Ended December 31,
(in millions) | 2020 |  | 2019 |  | 2018
FV-NI: |  |  |  |  |
Realized gains | $ | 302 |  |  | $ | 59 |  |  | $ | 79 |
Realized losses | 75 |  |  | 44 |  |  | 53 |
AFS: |  |  |  |  |
Realized gains | 24 |  |  | 36 |  |  | 3 |
Realized losses | 13 |  |  | 29 |  |  | 15 |
Duke Energy Progress |
Investment [Line Items] |
Summary of Investments in Debt and Equity Securities | The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.
| December 31, 2020 |  | December 31, 2019
| Gross |  | Gross |  |  |  | Gross |  | Gross |  |
| Unrealized |  | Unrealized |  |  |  | Unrealized |  | Unrealized |  |
| Holding |  | Holding |  | Estimated |  | Holding |  | Holding |  | Estimated
(in millions) | Gains |  | Losses |  | Fair Value |  | Gains |  | Losses |  | Fair Value
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 76 |  |  | $ | — |  |  | $ | — |  |  | $ | 53 |
Equity securities | 1,617 |  |  | 31 |  |  | 2,459 |  |  | 1,258 |  |  | 21 |  |  | 2,077 |
Corporate debt securities | 27 |  |  | — |  |  | 296 |  |  | 16 |  |  | — |  |  | 242 |
Municipal bonds | 16 |  |  | — |  |  | 279 |  |  | 10 |  |  | — |  |  | 272 |
U.S. government bonds | 26 |  |  | — |  |  | 412 |  |  | 16 |  |  | — |  |  | 403 |
Other debt securities | 1 |  |  | — |  |  | 6 |  |  | — |  |  | — |  |  | 4 |
Total NDTF Investments | $ | 1,687 |  |  | $ | 31 |  |  | $ | 3,528 |  |  | $ | 1,300 |  |  | $ | 21 |  |  | $ | 3,051 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 1 |  |  | $ | — |  |  | $ | — |  |  | $ | 2 |
Total Other Investments | $ | — |  |  | $ | — |  |  | $ | 1 |  |  | $ | — |  |  | $ | — |  |  | $ | 2 |
Total Investments | $ | 1,687 |  |  | $ | 31 |  |  | $ | 3,529 |  |  | $ | 1,300 |  |  | $ | 21 |  |  | $ | 3,053 |
Investments Classified by Contractual Maturity Date | The table below summarizes the maturity date for debt securities.
(in millions) | December 31, 2020
Due in one year or less | $ | 21 |
Due after one through five years | 259 |
Due after five through 10 years | 210 |
Due after 10 years | 503 |
Total | $ | 993 |
Schedule of Realized Gain (Loss) | Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the years ended December 31, 2020, 2019 and 2018, were as follows.
| Years Ended December 31,
(in millions) | 2020 |  | 2019 |  | 2018
FV-NI: |  |  |  |  |
Realized gains | $ | 52 |  |  | $ | 38 |  |  | $ | 68 |
Realized losses | 59 |  |  | 33 |  |  | 48 |
AFS: |  |  |  |  |
Realized gains | 24 |  |  | 7 |  |  | 2 |
Realized losses | 13 |  |  | 5 |  |  | 10 |
Duke Energy Florida |
Investment [Line Items] |
Summary of Investments in Debt and Equity Securities | The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS.
| December 31, 2020 |  | December 31, 2019
| Gross |  | Gross |  |  |  | Gross |  | Gross |  |
| Unrealized |  | Unrealized |  |  |  | Unrealized |  | Unrealized |  |
| Holding |  | Holding |  | Estimated |  | Holding |  | Holding |  | Estimated
(in millions) | Gains |  | Losses |  | Fair Value |  | Gains |  | Losses |  | Fair Value
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 71 |  |  | $ | — |  |  | $ | — |  |  | $ | 27 |
Equity securities | 79 |  |  | — |  |  | 91 |  |  | 351 |  |  | 26 |  |  | 430 |
U.S. government bonds | — |  |  | — |  |  | 474 |  |  | 1 |  |  | — |  |  | 275 |
Total NDTF Investments(a) | $ | 79 |  |  | $ | — |  |  | $ | 636 |  |  | $ | 352 |  |  | $ | 26 |  |  | $ | 732 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 1 |  |  | $ | — |  |  | $ | — |  |  | $ | 4 |
Municipal bonds | 3 |  |  | — |  |  | 26 |  |  | 3 |  |  | — |  |  | 51 |
Total Other Investments | $ | 3 |  |  | $ | — |  |  | $ | 27 |  |  | $ | 3 |  |  | $ | — |  |  | $ | 55 |
Total Investments | $ | 82 |  |  | $ | — |  |  | $ | 663 |  |  | $ | 355 |  |  | $ | 26 |  |  | $ | 787 |
(a) During the years ended December 31, 2020, and 2019, Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3.
Investments Classified by Contractual Maturity Date | The table below summarizes the maturity date for debt securities.
(in millions) | December 31, 2020
Due in one year or less | $ | 88 |
Due after one through five years | 308 |
Due after five through 10 years | 88 |
Due after 10 years | 16 |
Total | $ | 500 |
Schedule of Realized Gain (Loss) | Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the years ended December 31, 2020, 2019 and 2018, were as follows.
| Years Ended December 31,
(in millions) | 2020 |  | 2019 |  | 2018
FV-NI: |  |  |  |  |
Realized gains | $ | 250 |  |  | $ | 21 |  |  | $ | 11 |
Realized losses | 16 |  |  | 11 |  |  | 5 |
AFS: |  |  |  |  |
Realized gains | — |  |  | 29 |  |  | 1 |
Realized losses | — |  |  | 24 |  |  | 5 |
Duke Energy Indiana |
Investment [Line Items] |
Summary of Investments in Debt and Equity Securities | The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS.
| December 31, 2020 |  | December 31, 2019
| Gross |  | Gross |  |  |  | Gross |  | Gross |  |
| Unrealized |  | Unrealized |  |  |  | Unrealized |  | Unrealized |  |
| Holding |  | Holding |  | Estimated |  | Holding |  | Holding |  | Estimated
(in millions) | Gains |  | Losses |  | Fair Value |  | Gains |  | Losses |  | Fair Value
Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 1 |  |  | $ | — |  |  | $ | — |  |  | $ | — |
Equity securities | 58 |  |  | — |  |  | 97 |  |  | 43 |  |  | — |  |  | 81 |
Corporate debt securities | — |  |  | — |  |  | 3 |  |  | — |  |  | — |  |  | 6 |
Municipal bonds | 1 |  |  | — |  |  | 38 |  |  | 1 |  |  | — |  |  | 36 |
U.S. government bonds | — |  |  | — |  |  | 4 |  |  | — |  |  | — |  |  | 2 |
Total Investments | $ | 59 |  |  | $ | — |  |  | $ | 143 |  |  | $ | 44 |  |  | $ | — |  |  | $ | 125 |
Investments Classified by Contractual Maturity Date | The table below summarizes the maturity date for debt securities.
(in millions) | December 31, 2020
Due in one year or less | $ | 3 |
Due after one through five years | 17 |
Due after five through 10 years | 10 |
Due after 10 years | 15 |
Total | $ | 45 |

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