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Fair Value Measurements (Tables) | 6 Months Ended
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Jun. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the tables below for all Duke Energy Registrants exclude cash collateral, which is disclosed in Note 9. See Note 10 for additional information related to investments by major security type for the Duke Energy Registrants.
| June 30, 2018
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |  | Level 3 |  | Not Categorized |
NDTF equity securities | $ | 4,988 |  | $ | 4,918 |  | $ | — |  | $ | — |  | $ | 70 |
NDTF debt securities | 2,136 |  | 578 |  | 1,558 |  | — |  | — |
Other equity securities | 109 |  | 109 |  | — |  | — |  | — |
Other debt securities | 267 |  | 68 |  | 199 |  | — |  | — |
Derivative assets | 87 |  | 3 |  | 31 |  | 53 |  | — |
Total assets | 7,587 |  | 5,676 |  | 1,788 |  | 53 |  | 70 |
Derivative liabilities | (213 | ) | (1 | ) | (62 | ) | (150 | ) | — |
Net assets (liabilities) | $ | 7,374 |  | $ | 5,675 |  | $ | 1,726 |  | $ | (97 | ) | $ | 70 |
| December 31, 2017
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |  | Level 3 |  | Not Categorized |
NDTF equity securities | $ | 4,914 |  | $ | 4,840 |  | $ | — |  | $ | — |  | $ | 74 |
NDTF debt securities | 2,174 |  | 635 |  | 1,539 |  | — |  | — |
Other equity securities | 123 |  | 123 |  | — |  | — |  | — |
Other debt securities | 241 |  | 57 |  | 184 |  | — |  | — |
Derivative assets | 51 |  | 3 |  | 20 |  | 28 |  | — |
Total assets | 7,503 |  | 5,658 |  | 1,743 |  | 28 |  | 74 |
Derivative liabilities | (230 | ) | (2 | ) | (86 | ) | (142 | ) | — |
Net assets (liabilities) | $ | 7,273 |  | $ | 5,656 |  | $ | 1,657 |  | $ | (114 | ) | $ | 74 |
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs | The following tables provide reconciliations of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Amounts included in earnings for derivatives are primarily included in Cost of natural gas on the Duke Energy Registrants' Condensed Consolidated Statements of Operations and Comprehensive Income. Amounts included in changes of net assets on the Duke Energy Registrants' Condensed Consolidated Balance Sheets are included in regulatory assets or liabilities. All derivative assets and liabilities are presented on a net basis.
| Three Months Ended June 30, 2018 |  | Three Months Ended June 30, 2017
(in millions) | Investments |  |  | Derivatives (net) |  |  | Total |  |  | Investments |  |  | Derivatives (net) |  |  | Total |
Balance at beginning of period | $ | — |  |  | $ | (124 | ) |  | $ | (124 | ) |  | $ | 5 |  |  | $ | (135 | ) |  | $ | (130 | )
Total pretax realized or unrealized gains included in comprehensive income | — |  |  | — |  |  | — |  |  | 1 |  |  | — |  |  | 1 |
Purchases, sales, issuances and settlements: |  |  |  |  | — |  |  |  |  |  |  |
Purchases | — |  |  | 56 |  |  | 56 |  |  | — |  |  | 55 |  |  | 55 |
Sales | — |  |  | — |  |  | — |  |  | (6 | ) |  | — |  |  | (6 | )
Settlements | — |  |  | (15 | ) |  | (15 | ) |  | — |  |  | (9 | ) |  | (9 | )
Total losses included on the Condensed Consolidated Balance Sheet | — |  |  | (14 | ) |  | (14 | ) |  | — |  |  | (2 | ) |  | (2 | )
Balance at end of period | $ | — |  |  | $ | (97 | ) |  | $ | (97 | ) |  | $ | — |  |  | $ | (91 | ) |  | $ | (91 | )
| Six Months Ended June 30, 2018 |  | Six Months Ended June 30, 2017
(in millions) | Investments |  |  | Derivatives (net) |  |  | Total |  |  | Investments |  |  | Derivatives (net) |  |  | Total |
Balance at beginning of period | $ | — |  |  | $ | (114 | ) |  | $ | (114 | ) |  | $ | 5 |  |  | $ | (166 | ) |  | $ | (161 | )
Total pretax realized or unrealized gains included in comprehensive income | — |  |  | — |  |  | — |  |  | 1 |  |  | — |  |  | 1 |
Purchases, sales, issuances and settlements: |  |  |  |  |  |  |  |  |  |  |
Purchases | — |  |  | 56 |  |  | 56 |  |  | — |  |  | 55 |  |  | 55 |
Sales | — |  |  | — |  |  | — |  |  | (6 | ) |  | — |  |  | (6 | )
Settlements | — |  |  | (29 | ) |  | (29 | ) |  | — |  |  | (18 | ) |  | (18 | )
Total (losses) gains included on the Condensed Consolidated Balance Sheet | — |  |  | (10 | ) |  | (10 | ) |  | — |  |  | 38 |  |  | 38 |
Balance at end of period | $ | — |  |  | $ | (97 | ) |  | $ | (97 | ) |  | $ | — |  |  | $ | (91 | ) |  | $ | (91 | )
Quantitative Information Table - Level 3 | The following tables include quantitative information about the Duke Energy Registrants' derivatives classified as Level 3.
| June 30, 2018
| Fair Value |  |  |  |  |
Investment Type | (in millions) | Valuation Technique | Unobservable Input | Range
Duke Energy Ohio |  |  |  |  |  |  |
Financial Transmission Rights (FTRs) | $ | 9 |  | RTO auction pricing | FTR price – per megawatt-hour (MWh) | $ | 0.67 |  | - | $ | 3.32 |
Duke Energy Indiana |  |  |  |  |  |  |
FTRs | 44 |  | RTO auction pricing | FTR price – per MWh | (2.31 | ) | - | 11.01 |
Piedmont |  |  |  |  |  |
Natural gas contracts | (150 | ) | Discounted cash flow | Forward natural gas curves – price per million British thermal unit (MMBtu) | 1.88 |  | - | 3.42 |
Duke Energy |  |  |  |  |  |
Total Level 3 derivatives | $ | (97 | ) |  |  |  |  |
| December 31, 2017
| Fair Value |  |  |  |  |
Investment Type | (in millions) | Valuation Technique | Unobservable Input | Range
Duke Energy Ohio |  |  |  |  |  |  |
FTRs | $ | 1 |  | RTO auction pricing | FTR price – per MWh | $ | 0.07 |  | - | $ | 1.41 |
Duke Energy Indiana |  |  |  |  |  |  |
FTRs | 27 |  | RTO auction pricing | FTR price – per MWh | (0.77 | ) | - | 7.44 |
Piedmont |  |  |  |  |  |
Natural gas contracts | (142 | ) | Discounted cash flow | Forward natural gas curves – price per MMBtu | 2.10 |  | - | 2.88 |
Duke Energy |  |  |  |  |  |
Total Level 3 derivatives | $ | (114 | ) |  |  |  |  |
Schedule Of Long Term Debt Fair Value | The fair value and book value of long-term debt, including current maturities, is summarized in the following table. Estimates determined are not necessarily indicative of amounts that could have been settled in current markets. Fair value of long-term debt uses Level 2 measurements.
| June 30, 2018 |  | December 31, 2017
(in millions) | Book Value |  |  | Fair Value |  |  | Book Value |  |  | Fair Value |
Duke Energy(a) | $ | 52,715 |  |  | $ | 52,676 |  |  | $ | 52,279 |  |  | $ | 55,331 |
Duke Energy Carolinas | 10,394 |  |  | 11,028 |  |  | 10,103 |  |  | 11,372 |
Progress Energy | 18,194 |  |  | 19,357 |  |  | 17,837 |  |  | 20,000 |
Duke Energy Progress | 7,358 |  |  | 7,527 |  |  | 7,357 |  |  | 7,992 |
Duke Energy Florida | 7,452 |  |  | 7,945 |  |  | 7,095 |  |  | 7,953 |
Duke Energy Ohio | 2,066 |  |  | 2,162 |  |  | 2,067 |  |  | 2,249 |
Duke Energy Indiana | 3,782 |  |  | 4,223 |  |  | 3,783 |  |  | 4,464 |
Piedmont | 2,037 |  |  | 2,087 |  |  | 2,037 |  |  | 2,209 |
(a) | Book value of long-term debt includes $1.7 billion as of June 30, 2018, and December 31, 2017, of unamortized debt discount and premium, net in purchase accounting adjustments related to the mergers with Progress Energy and Piedmont that are excluded from fair value of long-term debt.
Duke Energy Carolinas [Member] |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets.
| June 30, 2018
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |  | Not Categorized |
NDTF equity securities | $ | 2,732 |  | $ | 2,662 |  | $ | — |  | $ | 70 |
NDTF debt securities | 1,049 |  | 164 |  | 885 |  | — |
Derivative assets | 3 |  | — |  | 3 |  | — |
Total assets | 3,784 |  | 2,826 |  | 888 |  | 70 |
Derivative liabilities | (19 | ) | — |  | (19 | ) | — |
Net assets | $ | 3,765 |  | $ | 2,826 |  | $ | 869 |  | $ | 70 |
| December 31, 2017
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |  | Not Categorized |
NDTF equity securities | $ | 2,692 |  | $ | 2,618 |  | $ | — |  | $ | 74 |
NDTF debt securities | 1,066 |  | 204 |  | 862 |  | — |
Derivative assets | 2 |  | — |  | 2 |  | — |
Total assets | 3,760 |  | 2,822 |  | 864 |  | 74 |
Derivative liabilities | (35 | ) | (1 | ) | (34 | ) | — |
Net assets | $ | 3,725 |  | $ | 2,821 |  | $ | 830 |  | $ | 74 |
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs | The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements.
| Investments
| Three Months Ended June 30, |  | Six Months Ended June 30,
(in millions) | 2018 |  |  | 2017 |  |  | 2018 |  |  | 2017 |
Balance at beginning of period | $ | — |  |  | $ | 3 |  |  | $ | — |  |  | $ | 3 |
Total pretax realized or unrealized gains included in comprehensive income | — |  |  | 1 |  |  | — |  |  | 1 |
Purchases, sales, issuances and settlements: |  |  |  |  |  |  |
Sales | — |  |  | (4 | ) |  | — |  |  | (4 | )
Balance at end of period | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |
Progress Energy [Member] |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets.
| June 30, 2018
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |
NDTF equity securities | $ | 2,256 |  | $ | 2,256 |  | $ | — |
NDTF debt securities | 1,087 |  | 414 |  | 673 |
Other debt securities | 58 |  | 11 |  | 47 |
Derivative assets | 5 |  | — |  | 5 |
Total assets | 3,406 |  | 2,681 |  | 725 |
Derivative liabilities | (35 | ) | — |  | (35 | )
Net assets | $ | 3,371 |  | $ | 2,681 |  | $ | 690 |
| December 31, 2017
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |
NDTF equity securities | $ | 2,222 |  | $ | 2,222 |  | $ | — |
NDTF debt securities | 1,108 |  | 431 |  | 677 |
Other debt securities | 59 |  | 12 |  | 47 |
Derivative assets | 3 |  | 1 |  | 2 |
Total assets | 3,392 |  | 2,666 |  | 726 |
Derivative liabilities | (36 | ) | (1 | ) | (35 | )
Net assets | $ | 3,356 |  | $ | 2,665 |  | $ | 691 |
Duke Energy Progress [Member] |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets.
| June 30, 2018
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |
NDTF equity securities | $ | 1,819 |  | $ | 1,819 |  | $ | — |
NDTF debt securities | 808 |  | 255 |  | 553 |
Other debt securities | 1 |  | 1 |  | — |
Derivative assets | 4 |  | 1 |  | 3 |
Total assets | 2,632 |  | 2,076 |  | 556 |
Derivative liabilities | (21 | ) | — |  | (21 | )
Net assets | $ | 2,611 |  | $ | 2,076 |  | $ | 535 |
| December 31, 2017
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |
NDTF equity securities | $ | 1,795 |  | $ | 1,795 |  | $ | — |
NDTF debt securities | 796 |  | 243 |  | 553 |
Other debt securities | 1 |  | 1 |  | — |
Derivative assets | 2 |  | 1 |  | 1 |
Total assets | 2,594 |  | 2,040 |  | 554 |
Derivative liabilities | (18 | ) | (1 | ) | (17 | )
Net assets | $ | 2,576 |  | $ | 2,039 |  | $ | 537 |
Duke Energy Florida [Member] |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets.
| June 30, 2018
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |
NDTF equity securities | $ | 437 |  | $ | 437 |  | $ | — |
NDTF debt securities | 279 |  | 159 |  | 120 |
Other debt securities | 48 |  | 1 |  | 47 |
Derivative assets | 1 |  | — |  | 1 |
Total assets | 765 |  | 597 |  | 168 |
Derivative liabilities | (5 | ) | — |  | (5 | )
Net assets | $ | 760 |  | $ | 597 |  | $ | 163 |
| December 31, 2017
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |
NDTF equity securities | $ | 427 |  | $ | 427 |  | $ | — |
NDTF debt securities | 312 |  | 188 |  | 124 |
Other debt securities | 48 |  | 1 |  | 47 |
Derivative assets | 1 |  | — |  | 1 |
Total assets | 788 |  | 616 |  | 172 |
Derivative liabilities | (12 | ) | — |  | (12 | )
Net assets | $ | 776 |  | $ | 616 |  | $ | 160 |
Duke Energy Ohio [Member] |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets.
| June 30, 2018 |  | December 31, 2017
(in millions) | Total Fair Value |  | Level 2 |  | Level 3 |  |  | Total Fair Value |  | Level 2 |  | Level 3 |
Derivative assets | $ | 9 |  | $ | — |  | $ | 9 |  |  | $ | 1 |  | $ | — |  | $ | 1 |
Derivative liabilities | (4 | ) | (4 | ) | — |  |  | (5 | ) | (5 | ) | — |
Net assets (liabilities) | $ | 5 |  | $ | (4 | ) | $ | 9 |  |  | $ | (4 | ) | $ | (5 | ) | $ | 1 |
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs | The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements.
| Derivatives (net)
| Three Months Ended June 30, |  | Six Months Ended June 30,
(in millions) | 2018 |  |  | 2017 |  |  | 2018 |  |  | 2017 |
Balance at beginning of period | $ | 1 |  |  | $ | 1 |  |  | $ | 1 |  |  | $ | 5 |
Purchases, sales, issuances and settlements: |  |  |  |  |  |  |
Purchases | 7 |  |  | 3 |  |  | 7 |  |  | 3 |
Settlements | (1 | ) |  | (1 | ) |  | (1 | ) |  | (2 | )
Total gains (losses) included on the Condensed Consolidated Balance Sheet | 2 |  |  | — |  |  | 2 |  |  | (3 | )
Balance at end of period | $ | 9 |  |  | $ | 3 |  |  | $ | 9 |  |  | $ | 3 |
Duke Energy Indiana [Member] |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets.
| June 30, 2018
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |  | Level 3 |
Other equity securities | $ | 74 |  | $ | 74 |  | $ | — |  | $ | — |
Other debt securities | 41 |  | — |  | 41 |  | — |
Derivative assets | 45 |  | 1 |  | — |  | 44 |
Total assets | $ | 160 |  | $ | 75 |  | $ | 41 |  | $ | 44 |
| December 31, 2017
(in millions) | Total Fair Value |  | Level 1 |  | Level 2 |  | Level 3 |
Other equity securities | $ | 97 |  | $ | 97 |  | $ | — |  | $ | — |
Other debt securities | 31 |  | — |  | 31 |  | — |
Derivative assets | 27 |  | — |  | — |  | 27 |
Total assets | $ | 155 |  | $ | 97 |  | $ | 31 |  | $ | 27 |
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs | The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements.
| Derivatives (net)
| Three Months Ended June 30, |  | Six Months Ended June 30,
(in millions) | 2018 |  |  | 2017 |  |  | 2018 |  |  | 2017 |
Balance at beginning of period | $ | 7 |  |  | $ | 9 |  |  | $ | 27 |  |  | $ | 16 |
Purchases, sales, issuances and settlements: |  |  |  |  |  |  |
Purchases | 49 |  |  | 52 |  |  | 49 |  |  | 52 |
Settlements | (14 | ) |  | (9 | ) |  | (28 | ) |  | (16 | )
Total gains (losses) included on the Condensed Consolidated Balance Sheet | 2 |  |  | (1 | ) |  | (4 | ) |  | (1 | )
Balance at end of period | $ | 44 |  |  | $ | 51 |  |  | $ | 44 |  |  | $ | 51 |
Piedmont Natural Gas [Member] |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Fair Value Measurement Amounts For Assets And Liabilities | The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets.
| June 30, 2018
(in millions) | Total Fair Value |  | Level 1 |  | Level 3 |
Derivative assets | $ | 2 |  | $ | 2 |  | $ | — |
Derivative liabilities | (150 | ) | — |  | (150 | )
Net (liabilities) assets | $ | (148 | ) | $ | 2 |  | $ | (150 | )
| December 31, 2017
(in millions) | Total Fair Value |  | Level 1 |  | Level 3 |
Other debt securities | $ | 1 |  | $ | 1 |  | $ | — |
Derivative assets | 2 |  | 2 |  | — |
Total assets | 3 |  | 3 |  | — |
Derivative liabilities | (142 | ) | — |  | (142 | )
Net (liabilities) assets | $ | (139 | ) | $ | 3 |  | $ | (142 | )
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs | The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements.
| Derivatives (net)
| Three Months Ended June 30, |  | Six Months Ended June 30,
(in millions) | 2018 |  |  | 2017 |  |  | 2018 |  |  | 2017 |
Balance at beginning of period | $ | (132 | ) |  | $ | (145 | ) |  | $ | (142 | ) |  | $ | (187 | )
Total (losses) gains and settlements | (18 | ) |  | — |  |  | (8 | ) |  | 42 |
Balance at end of period | $ | (150 | ) |  | $ | (145 | ) |  | $ | (150 | ) |  | $ | (145 | )

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