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Investments in Debt and Equity Securities (Tables) | 6 Months Ended
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Jun. 30, 2019
Debt Securities, Available-for-sale [Line Items] |
Debt Securities, Trading, and Equity Securities, FV-NI | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 114 |  |  | $ | — |  |  | $ | — |  |  | $ | 88 |
Equity securities | 3,076 |  |  | 36 |  |  | 5,178 |  |  | 2,402 |  |  | 95 |  |  | 4,475 |
Corporate debt securities | 30 |  |  | 1 |  |  | 571 |  |  | 4 |  |  | 13 |  |  | 566 |
Municipal bonds | 10 |  |  | — |  |  | 318 |  |  | 1 |  |  | 4 |  |  | 353 |
U.S. government bonds | 34 |  |  | 1 |  |  | 1,270 |  |  | 14 |  |  | 12 |  |  | 1,076 |
Other debt securities | 3 |  |  | 1 |  |  | 152 |  |  | — |  |  | 2 |  |  | 148 |
Total NDTF Investments | $ | 3,153 |  |  | $ | 39 |  |  | $ | 7,603 |  |  | $ | 2,421 |  |  | $ | 126 |  |  | $ | 6,706 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 49 |  |  | $ | — |  |  | $ | — |  |  | $ | 22 |
Equity securities | 49 |  |  | — |  |  | 112 |  |  | 36 |  |  | 1 |  |  | 99 |
Corporate debt securities | 2 |  |  | — |  |  | 60 |  |  | — |  |  | 2 |  |  | 60 |
Municipal bonds | 3 |  |  | 1 |  |  | 90 |  |  | — |  |  | 1 |  |  | 85 |
U.S. government bonds | 2 |  |  | — |  |  | 51 |  |  | 1 |  |  | — |  |  | 45 |
Other debt securities | — |  |  | — |  |  | 65 |  |  | — |  |  | 1 |  |  | 58 |
Total Other Investments | $ | 56 |  |  | $ | 1 |  |  | $ | 427 |  |  | $ | 37 |  |  | $ | 5 |  |  | $ | 369 |
Total Investments | $ | 3,209 |  |  | $ | 40 |  |  | $ | 8,030 |  |  | $ | 2,458 |  |  | $ | 131 |  |  | $ | 7,075 |
Debt Securities, Available-for-sale | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 114 |  |  | $ | — |  |  | $ | — |  |  | $ | 88 |
Equity securities | 3,076 |  |  | 36 |  |  | 5,178 |  |  | 2,402 |  |  | 95 |  |  | 4,475 |
Corporate debt securities | 30 |  |  | 1 |  |  | 571 |  |  | 4 |  |  | 13 |  |  | 566 |
Municipal bonds | 10 |  |  | — |  |  | 318 |  |  | 1 |  |  | 4 |  |  | 353 |
U.S. government bonds | 34 |  |  | 1 |  |  | 1,270 |  |  | 14 |  |  | 12 |  |  | 1,076 |
Other debt securities | 3 |  |  | 1 |  |  | 152 |  |  | — |  |  | 2 |  |  | 148 |
Total NDTF Investments | $ | 3,153 |  |  | $ | 39 |  |  | $ | 7,603 |  |  | $ | 2,421 |  |  | $ | 126 |  |  | $ | 6,706 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 49 |  |  | $ | — |  |  | $ | — |  |  | $ | 22 |
Equity securities | 49 |  |  | — |  |  | 112 |  |  | 36 |  |  | 1 |  |  | 99 |
Corporate debt securities | 2 |  |  | — |  |  | 60 |  |  | — |  |  | 2 |  |  | 60 |
Municipal bonds | 3 |  |  | 1 |  |  | 90 |  |  | — |  |  | 1 |  |  | 85 |
U.S. government bonds | 2 |  |  | — |  |  | 51 |  |  | 1 |  |  | — |  |  | 45 |
Other debt securities | — |  |  | — |  |  | 65 |  |  | — |  |  | 1 |  |  | 58 |
Total Other Investments | $ | 56 |  |  | $ | 1 |  |  | $ | 427 |  |  | $ | 37 |  |  | $ | 5 |  |  | $ | 369 |
Total Investments | $ | 3,209 |  |  | $ | 40 |  |  | $ | 8,030 |  |  | $ | 2,458 |  |  | $ | 131 |  |  | $ | 7,075 |
Investments Classified by Contractual Maturity Date | The table below summarizes the maturity date for debt securities.
| June 30, 2019
|  |  | Duke |  |  |  |  | Duke |  |  | Duke |  |  | Duke |
| Duke |  |  | Energy |  |  | Progress |  |  | Energy |  |  | Energy |  |  | Energy |
(in millions) | Energy |  |  | Carolinas |  |  | Energy |  |  | Progress |  |  | Florida |  |  | Indiana |
Due in one year or less | $ | 365 |  |  | $ | 43 |  |  | $ | 315 |  |  | $ | 29 |  |  | $ | 286 |  |  | $ | 4 |
Due after one through five years | 527 |  |  | 213 |  |  | 265 |  |  | 257 |  |  | 8 |  |  | 15 |
Due after five through 10 years | 499 |  |  | 242 |  |  | 203 |  |  | 192 |  |  | 11 |  |  | 4 |
Due after 10 years | 1,186 |  |  | 622 |  |  | 458 |  |  | 428 |  |  | 30 |  |  | 19 |
Total | $ | 2,577 |  |  | $ | 1,120 |  |  | $ | 1,241 |  |  | $ | 906 |  |  | $ | 335 |  |  | $ | 42 |
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 three and six months ended June 30, 2019, and 2018, were as follows.
| Three Months Ended |  | Six Months Ended
(in millions) | June 30, 2019 |  | June 30, 2018 |  | June 30, 2019 |  | June 30, 2018
FV-NI: |  |  |  |  |  |  |
Realized gains | $ | 66 |  |  | $ | 47 |  |  | $ | 101 |  |  | $ | 66 |
Realized losses | 63 |  |  | 31 |  |  | 93 |  |  | 44 |
AFS: |  |  |  |  |  |  |
Realized gains | 47 |  |  | 5 |  |  | 57 |  |  | 10 |
Realized losses | 36 |  |  | 12 |  |  | 47 |  |  | 25 |
Duke Energy Carolinas [Member] |
Debt Securities, Available-for-sale [Line Items] |
Debt Securities, Trading, and Equity Securities, FV-NI | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 41 |  |  | $ | — |  |  | $ | — |  |  | $ | 29 |
Equity securities | 1,671 |  |  | 9 |  |  | 2,883 |  |  | 1,309 |  |  | 54 |  |  | 2,484 |
Corporate debt securities | 18 |  |  | 1 |  |  | 360 |  |  | 2 |  |  | 9 |  |  | 341 |
Municipal bonds | 2 |  |  | — |  |  | 63 |  |  | — |  |  | 1 |  |  | 81 |
U.S. government bonds | 17 |  |  | 1 |  |  | 556 |  |  | 5 |  |  | 8 |  |  | 475 |
Other debt securities | 3 |  |  | 1 |  |  | 141 |  |  | — |  |  | 2 |  |  | 143 |
Total NDTF Investments | $ | 1,711 |  |  | $ | 12 |  |  | $ | 4,044 |  |  | $ | 1,316 |  |  | $ | 74 |  |  | $ | 3,553 |
Debt Securities, Available-for-sale | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 41 |  |  | $ | — |  |  | $ | — |  |  | $ | 29 |
Equity securities | 1,671 |  |  | 9 |  |  | 2,883 |  |  | 1,309 |  |  | 54 |  |  | 2,484 |
Corporate debt securities | 18 |  |  | 1 |  |  | 360 |  |  | 2 |  |  | 9 |  |  | 341 |
Municipal bonds | 2 |  |  | — |  |  | 63 |  |  | — |  |  | 1 |  |  | 81 |
U.S. government bonds | 17 |  |  | 1 |  |  | 556 |  |  | 5 |  |  | 8 |  |  | 475 |
Other debt securities | 3 |  |  | 1 |  |  | 141 |  |  | — |  |  | 2 |  |  | 143 |
Total NDTF Investments | $ | 1,711 |  |  | $ | 12 |  |  | $ | 4,044 |  |  | $ | 1,316 |  |  | $ | 74 |  |  | $ | 3,553 |
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 three and six months ended June 30, 2019, and 2018, were as follows.
| Three Months Ended |  | Six Months Ended
(in millions) | June 30, 2019 |  | June 30, 2018 |  | June 30, 2019 |  | June 30, 2018
FV-NI: |  |  |  |  |  |  |
Realized gains | $ | 44 |  |  | $ | 26 |  |  | $ | 67 |  |  | $ | 36 |
Realized losses | 48 |  |  | 17 |  |  | 69 |  |  | 22 |
AFS: |  |  |  |  |  |  |
Realized gains | 16 |  |  | 4 |  |  | 25 |  |  | 9 |
Realized losses | 11 |  |  | 8 |  |  | 21 |  |  | 18 |
Progress Energy [Member] |
Debt Securities, Available-for-sale [Line Items] |
Debt Securities, Trading, and Equity Securities, FV-NI | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 73 |  |  | $ | — |  |  | $ | — |  |  | $ | 59 |
Equity securities | 1,405 |  |  | 27 |  |  | 2,295 |  |  | 1,093 |  |  | 41 |  |  | 1,991 |
Corporate debt securities | 12 |  |  | — |  |  | 211 |  |  | 2 |  |  | 4 |  |  | 225 |
Municipal bonds | 8 |  |  | — |  |  | 255 |  |  | 1 |  |  | 3 |  |  | 272 |
U.S. government bonds | 17 |  |  | — |  |  | 714 |  |  | 9 |  |  | 4 |  |  | 601 |
Other debt securities | — |  |  | — |  |  | 11 |  |  | — |  |  | — |  |  | 5 |
Total NDTF Investments | $ | 1,442 |  |  | $ | 27 |  |  | $ | 3,559 |  |  | $ | 1,105 |  |  | $ | 52 |  |  | $ | 3,153 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 47 |  |  | $ | — |  |  | $ | — |  |  | $ | 17 |
Municipal bonds | 3 |  |  | — |  |  | 50 |  |  | — |  |  | — |  |  | 47 |
Total Other Investments | $ | 3 |  |  | $ | — |  |  | $ | 97 |  |  | $ | — |  |  | $ | — |  |  | $ | 64 |
Total Investments | $ | 1,445 |  |  | $ | 27 |  |  | $ | 3,656 |  |  | $ | 1,105 |  |  | $ | 52 |  |  | $ | 3,217 |
Debt Securities, Available-for-sale | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 73 |  |  | $ | — |  |  | $ | — |  |  | $ | 59 |
Equity securities | 1,405 |  |  | 27 |  |  | 2,295 |  |  | 1,093 |  |  | 41 |  |  | 1,991 |
Corporate debt securities | 12 |  |  | — |  |  | 211 |  |  | 2 |  |  | 4 |  |  | 225 |
Municipal bonds | 8 |  |  | — |  |  | 255 |  |  | 1 |  |  | 3 |  |  | 272 |
U.S. government bonds | 17 |  |  | — |  |  | 714 |  |  | 9 |  |  | 4 |  |  | 601 |
Other debt securities | — |  |  | — |  |  | 11 |  |  | — |  |  | — |  |  | 5 |
Total NDTF Investments | $ | 1,442 |  |  | $ | 27 |  |  | $ | 3,559 |  |  | $ | 1,105 |  |  | $ | 52 |  |  | $ | 3,153 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 47 |  |  | $ | — |  |  | $ | — |  |  | $ | 17 |
Municipal bonds | 3 |  |  | — |  |  | 50 |  |  | — |  |  | — |  |  | 47 |
Total Other Investments | $ | 3 |  |  | $ | — |  |  | $ | 97 |  |  | $ | — |  |  | $ | — |  |  | $ | 64 |
Total Investments | $ | 1,445 |  |  | $ | 27 |  |  | $ | 3,656 |  |  | $ | 1,105 |  |  | $ | 52 |  |  | $ | 3,217 |
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 three and six months ended June 30, 2019, and 2018, were as follows.
| Three Months Ended | Six Months Ended
(in millions) | June 30, 2019 |  | June 30, 2018 |  | June 30, 2019 |  | June 30, 2018
FV-NI: |  |  |  |  |  |  |
Realized gains | $ | 22 |  |  | $ | 21 |  |  | $ | 34 |  |  | $ | 30 |
Realized losses | 15 |  |  | 14 |  |  | 24 |  |  | 22 |
AFS: |  |  |  |  |  |  |
Realized gains | 30 |  |  | 1 |  |  | 31 |  |  | 1 |
Realized losses | 25 |  |  | 4 |  |  | 26 |  |  | 7 |
Duke Energy Progress [Member] |
Debt Securities, Available-for-sale [Line Items] |
Debt Securities, Trading, and Equity Securities, FV-NI | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 42 |  |  | $ | — |  |  | $ | — |  |  | $ | 46 |
Equity securities | 1,092 |  |  | 24 |  |  | 1,886 |  |  | 833 |  |  | 30 |  |  | 1,588 |
Corporate debt securities | 12 |  |  | — |  |  | 211 |  |  | 2 |  |  | 3 |  |  | 171 |
Municipal bonds | 8 |  |  | — |  |  | 255 |  |  | 1 |  |  | 3 |  |  | 271 |
U.S. government bonds | 16 |  |  | — |  |  | 429 |  |  | 6 |  |  | 3 |  |  | 415 |
Other debt securities | — |  |  | — |  |  | 11 |  |  | — |  |  | — |  |  | 3 |
Total NDTF Investments | $ | 1,128 |  |  | $ | 24 |  |  | $ | 2,834 |  |  | $ | 842 |  |  | $ | 39 |  |  | $ | 2,494 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 2 |  |  | $ | — |  |  | $ | — |  |  | $ | 6 |
Total Other Investments | $ | — |  |  | $ | — |  |  | $ | 2 |  |  | $ | — |  |  | $ | — |  |  | $ | 6 |
Total Investments | $ | 1,128 |  |  | $ | 24 |  |  | $ | 2,836 |  |  | $ | 842 |  |  | $ | 39 |  |  | $ | 2,500 |
Debt Securities, Available-for-sale | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 42 |  |  | $ | — |  |  | $ | — |  |  | $ | 46 |
Equity securities | 1,092 |  |  | 24 |  |  | 1,886 |  |  | 833 |  |  | 30 |  |  | 1,588 |
Corporate debt securities | 12 |  |  | — |  |  | 211 |  |  | 2 |  |  | 3 |  |  | 171 |
Municipal bonds | 8 |  |  | — |  |  | 255 |  |  | 1 |  |  | 3 |  |  | 271 |
U.S. government bonds | 16 |  |  | — |  |  | 429 |  |  | 6 |  |  | 3 |  |  | 415 |
Other debt securities | — |  |  | — |  |  | 11 |  |  | — |  |  | — |  |  | 3 |
Total NDTF Investments | $ | 1,128 |  |  | $ | 24 |  |  | $ | 2,834 |  |  | $ | 842 |  |  | $ | 39 |  |  | $ | 2,494 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 2 |  |  | $ | — |  |  | $ | — |  |  | $ | 6 |
Total Other Investments | $ | — |  |  | $ | — |  |  | $ | 2 |  |  | $ | — |  |  | $ | — |  |  | $ | 6 |
Total Investments | $ | 1,128 |  |  | $ | 24 |  |  | $ | 2,836 |  |  | $ | 842 |  |  | $ | 39 |  |  | $ | 2,500 |
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 three and six months ended June 30, 2019, and 2018, were as follows.
| Three Months Ended | Six Months Ended
(in millions) | June 30, 2019 |  | June 30, 2018 |  | June 30, 2019 |  | June 30, 2018
FV-NI: |  |  |  |  |  |  |
Realized gains | $ | 7 |  |  | $ | 17 |  |  | $ | 17 |  |  | $ | 25 |
Realized losses | 7 |  |  | 12 |  |  | 15 |  |  | 20 |
AFS: |  |  |  |  |  |  |
Realized gains | 1 |  |  | 1 |  |  | 2 |  |  | 1 |
Realized losses | 1 |  |  | 3 |  |  | 2 |  |  | 5 |
Duke Energy Florida [Member] |
Debt Securities, Available-for-sale [Line Items] |
Debt Securities, Trading, and Equity Securities, FV-NI | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 31 |  |  | $ | — |  |  | $ | — |  |  | $ | 13 |
Equity securities | 313 |  |  | 3 |  |  | 409 |  |  | 260 |  |  | 11 |  |  | 403 |
Corporate debt securities | — |  |  | — |  |  | — |  |  | — |  |  | 1 |  |  | 54 |
Municipal bonds | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
U.S. government bonds | 1 |  |  | — |  |  | 285 |  |  | 3 |  |  | 1 |  |  | 186 |
Other debt securities | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 2 |
Total NDTF Investments(a) | $ | 314 |  |  | $ | 3 |  |  | $ | 725 |  |  | $ | 263 |  |  | $ | 13 |  |  | $ | 659 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 2 |  |  | $ | — |  |  | $ | — |  |  | $ | 1 |
Municipal bonds | 3 |  |  | — |  |  | 50 |  |  | — |  |  | — |  |  | 47 |
Total Other Investments | $ | 3 |  |  | $ | — |  |  | $ | 52 |  |  | $ | — |  |  | $ | — |  |  | $ | 48 |
Total Investments | $ | 317 |  |  | $ | 3 |  |  | $ | 777 |  |  | $ | 263 |  |  | $ | 13 |  |  | $ | 707 |
(a) During the six months ended June 30, 2019, Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of Crystal River Unit 3.
Debt Securities, Available-for-sale | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
NDTF |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 31 |  |  | $ | — |  |  | $ | — |  |  | $ | 13 |
Equity securities | 313 |  |  | 3 |  |  | 409 |  |  | 260 |  |  | 11 |  |  | 403 |
Corporate debt securities | — |  |  | — |  |  | — |  |  | — |  |  | 1 |  |  | 54 |
Municipal bonds | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 1 |
U.S. government bonds | 1 |  |  | — |  |  | 285 |  |  | 3 |  |  | 1 |  |  | 186 |
Other debt securities | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 2 |
Total NDTF Investments(a) | $ | 314 |  |  | $ | 3 |  |  | $ | 725 |  |  | $ | 263 |  |  | $ | 13 |  |  | $ | 659 |
Other Investments |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | — |  |  | $ | — |  |  | $ | 2 |  |  | $ | — |  |  | $ | — |  |  | $ | 1 |
Municipal bonds | 3 |  |  | — |  |  | 50 |  |  | — |  |  | — |  |  | 47 |
Total Other Investments | $ | 3 |  |  | $ | — |  |  | $ | 52 |  |  | $ | — |  |  | $ | — |  |  | $ | 48 |
Total Investments | $ | 317 |  |  | $ | 3 |  |  | $ | 777 |  |  | $ | 263 |  |  | $ | 13 |  |  | $ | 707 |
(a) During the six months ended June 30, 2019, Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of Crystal River Unit 3.
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 three and six months ended June 30, 2019, and 2018, were as follows.
| Three Months Ended | Six Months Ended
(in millions) | June 30, 2019 |  | June 30, 2018 |  | June 30, 2019 |  | June 30, 2018
FV-NI: |  |  |  |  |  |  |
Realized gains | $ | 15 |  |  | $ | 4 |  |  | $ | 17 |  |  | $ | 5 |
Realized losses | 8 |  |  | 2 |  |  | 9 |  |  | 2 |
AFS: |  |  |  |  |  |  |
Realized gains | 29 |  |  | — |  |  | 29 |  |  | — |
Realized losses | 24 |  |  | 1 |  |  | 24 |  |  | 2 |
Duke Energy Indiana [Member] |
Debt Securities, Available-for-sale [Line Items] |
Debt Securities, Trading, and Equity Securities, FV-NI | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
Investments |  |  |  |  |  |  |  |  |  |  |
Equity securities | $ | 37 |  |  | $ | — |  |  | $ | 74 |  |  | $ | 29 |  |  | $ | — |  |  | $ | 67 |
Corporate debt securities | — |  |  | — |  |  | 7 |  |  | — |  |  | — |  |  | 8 |
Municipal bonds | — |  |  | 1 |  |  | 34 |  |  | — |  |  | 1 |  |  | 33 |
U.S. government bonds | — |  |  | — |  |  | 1 |  |  | — |  |  | — |  |  | — |
Total Investments | $ | 37 |  |  | $ | 1 |  |  | $ | 116 |  |  | $ | 29 |  |  | $ | 1 |  |  | $ | 108 |
Debt Securities, Available-for-sale | 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.
| June 30, 2019 |  | December 31, 2018
| Gross |  |  | Gross |  |  |  |  | Gross |  |  | Gross |  |  |
| Unrealized |  |  | Unrealized |  |  | Estimated |  |  | Unrealized |  |  | Unrealized |  |  | Estimated |
| Holding |  |  | Holding |  |  | Fair |  |  | Holding |  |  | Holding |  |  | Fair |
(in millions) | Gains |  |  | Losses |  |  | Value |  |  | Gains |  |  | Losses |  |  | Value |
Investments |  |  |  |  |  |  |  |  |  |  |
Equity securities | $ | 37 |  |  | $ | — |  |  | $ | 74 |  |  | $ | 29 |  |  | $ | — |  |  | $ | 67 |
Corporate debt securities | — |  |  | — |  |  | 7 |  |  | — |  |  | — |  |  | 8 |
Municipal bonds | — |  |  | 1 |  |  | 34 |  |  | — |  |  | 1 |  |  | 33 |
U.S. government bonds | — |  |  | — |  |  | 1 |  |  | — |  |  | — |  |  | — |
Total Investments | $ | 37 |  |  | $ | 1 |  |  | $ | 116 |  |  | $ | 29 |  |  | $ | 1 |  |  | $ | 108 |

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