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Income Taxes (Tables) | 12 Months Ended
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Dec. 31, 2018
Income Tax Disclosure [Line Items] |
Schedule of Components of Income Tax Expense (Benefit) | Components of Income Tax Expense
| Year Ended December 31, 2018
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Current income taxes |  |  |  |  |  |  |  |
Federal | $ | (647 | ) | $ | (8 | ) | $ | (135 | ) | $ | (71 | ) | $ | (49 | ) | $ | 20 |  | $ | 29 |  | $ | 67 |
State | (11 | ) | 6 |  | (5 | ) | (5 | ) | (10 | ) | (1 | ) | 3 |  | 1 |
Foreign | 3 |  | — |  | — |  | — |  | — |  | — |  | — |  | — |
Total current income taxes | (655 | ) | (2 | ) | (140 | ) | (76 | ) | (59 | ) | 19 |  | 32 |  | 68 |
Deferred income taxes |  |  |  |  |  |  |  |
Federal | 1,064 |  | 299 |  | 341 |  | 256 |  | 115 |  | 21 |  | 74 |  | (36 | )
State | 49 |  | 11 |  | 20 |  | (17 | ) | 45 |  | 3 |  | 22 |  | 5 |
Total deferred income taxes(a)(b) | 1,113 |  | 310 |  | 361 |  | 239 |  | 160 |  | 24 |  | 96 |  | (31 | )
Investment tax credit amortization | (10 | ) | (5 | ) | (3 | ) | (3 | ) | — |  | — |  | — |  | — |
Income tax expense from continuing operations | 448 |  | 303 |  | 218 |  | 160 |  | 101 |  | 43 |  | 128 |  | 37 |
Tax benefit from discontinued operations | (26 | ) | — |  | — |  | — |  | — |  | — |  | — |  | — |
Total income tax expense included in Consolidated Statements of Operations | $ | 422 |  | $ | 303 |  | $ | 218 |  | $ | 160 |  | $ | 101 |  | $ | 43 |  | $ | 128 |  | $ | 37 |
(a) | Includes benefits of NOL carryforwards and tax credit carryforwards of $22 million at Duke Energy Carolinas, $293 million at Progress Energy, $59 million at Duke Energy Progress, $219 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $21 million at Duke Energy Indiana and $39 million at Piedmont. In addition, total deferred income taxes includes utilization of NOL carryforwards and tax credit carryforwards of $18 million at Duke Energy.
(b) | For the year ended December 31, 2018, the Company has revised the December 31, 2017, estimates of the income tax effects of the Tax Act, in accordance with SAB 118. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense.
| Year Ended December 31, 2017 |
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Current income taxes |  |  |  |  |  |  |  |
Federal | $ | (247 | ) | $ | 221 |  | $ | (436 | ) | $ | (95 | ) | $ | (188 | ) | $ | (37 | ) | $ | 128 |  | $ | (90 | )
State | 4 |  | 20 |  | (5 | ) | 2 |  | (11 | ) | 2 |  | 21 |  | (3 | )
Foreign | 3 |  | — |  | — |  | — |  | — |  | — |  | — |  | — |
Total current income taxes | (240 | ) | 241 |  | (441 | ) | (93 | ) | (199 | ) | (35 | ) | 149 |  | (93 | )
Deferred income taxes |  |  |  |  |  |  |  |
Federal | 1,344 |  | 381 |  | 664 |  | 378 |  | 194 |  | 99 |  | 138 |  | 147 |
State | 102 |  | 35 |  | 44 |  | 10 |  | 51 |  | (4 | ) | 14 |  | 8 |
Total deferred income taxes(a)(b) | 1,446 |  | 416 |  | 708 |  | 388 |  | 245 |  | 95 |  | 152 |  | 155 |
Investment tax credit amortization | (10 | ) | (5 | ) | (3 | ) | (3 | ) | — |  | (1 | ) | — |  | — |
Income tax expense from continuing operations | 1,196 |  | 652 |  | 264 |  | 292 |  | 46 |  | 59 |  | 301 |  | 62 |
Tax benefit from discontinued operations | (6 | ) | — |  | — |  | — |  | — |  | — |  | — |  | — |
Total income tax expense included in Consolidated Statements of Operations | $ | 1,190 |  | $ | 652 |  | $ | 264 |  | $ | 292 |  | $ | 46 |  | $ | 59 |  | $ | 301 |  | $ | 62 |
(a) | Includes utilization of NOL carryforwards and tax credit carryforwards of $428 million at Duke Energy, $74 million at Progress Energy, $36 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $42 million at Duke Energy Indiana and $79 million at Piedmont. In addition, total deferred income taxes includes benefits of NOL carryforwards and tax credit carryforwards of $10 million at Duke Energy Carolinas and $1 million at Duke Energy Progress.
(b) | As a result of the Tax Act, Duke Energy's deferred tax assets and liabilities were revalued as of December 31, 2017. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense.
| Year Ended December 31, 2016
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |
Current income taxes |  |  |  |  |  |  |
Federal | $ | — |  | $ | 139 |  | $ | 15 |  | $ | (59 | ) | $ | 76 |  | $ | (7 | ) | $ | 7 |
State | (15 | ) | 25 |  | (19 | ) | (25 | ) | 22 |  | (13 | ) | 6 |
Foreign | 2 |  | — |  | — |  | — |  | — |  | — |  | — |
Total current income taxes | (13 | ) | 164 |  | (4 | ) | (84 | ) | 98 |  | (20 | ) | 13 |
Deferred income taxes |  |  |  |  |  |  |
Federal | 1,064 |  | 430 |  | 486 |  | 350 |  | 199 |  | 88 |  | 202 |
State | 117 |  | 45 |  | 50 |  | 40 |  | 25 |  | 11 |  | 11 |
Total deferred income taxes(a) | 1,181 |  | 475 |  | 536 |  | 390 |  | 224 |  | 99 |  | 213 |
Investment tax credit amortization | (12 | ) | (5 | ) | (5 | ) | (5 | ) | — |  | (1 | ) | (1 | )
Income tax expense from continuing operations | 1,156 |  | 634 |  | 527 |  | 301 |  | 322 |  | 78 |  | 225 |
Tax (benefit) expense from discontinued operations | (30 | ) | — |  | 1 |  | — |  | — |  | (36 | ) | — |
Total income tax expense included in Consolidated Statements of Operations | $ | 1,126 |  | $ | 634 |  | $ | 528 |  | $ | 301 |  | $ | 322 |  | $ | 42 |  | $ | 225 |
(a) | Includes benefits of NOL carryforwards and utilization of NOL and tax credit carryforwards of $648 million at Duke Energy, $4 million at Duke Energy Carolinas, $190 million at Progress Energy, $60 million at Duke Energy Progress, $49 million at Duke Energy Florida, $26 million at Duke Energy Ohio and $58 million at Duke Energy Indiana.
| Piedmont
| Two Months Ended | Year Ended October 31,
(in millions) | December 31, 2016 | 2016
Current income taxes |  |
Federal | $ | 4 |  | $ | 27 |
State | (2 | ) | 12 |
Total current income taxes | 2 |  | 39 |
Deferred income taxes |  |
Federal | 24 |  | 79 |
State | 6 |  | 6 |
Total deferred income taxes(a) | 30 |  | 85 |
Total income tax expense from continuing operations included in Consolidated Statements of Operations | $ | 32 |  | $ | 124 |
Schedule of Income before Income Tax, Domestic and Foreign | Duke Energy Income from Continuing Operations before Income Taxes
| Years Ended December 31,
(in millions) | 2018 |  | 2017 |  | 2016
Domestic(a) | $ | 3,018 |  |  | $ | 4,207 |  |  | $ | 3,689 |
Foreign | 55 |  |  | 59 |  |  | 45 |
Income from continuing operations before income taxes | $ | 3,073 |  |  | $ | 4,266 |  |  | $ | 3,734 |
(a) | Includes a $16 million expense in 2017 related to the Tax Act impact on equity earnings included within Equity in earnings (losses) of unconsolidated affiliates on the Consolidated Statement of Operations.
Summary of Effective Tax Rates | The following tables present a reconciliation of income tax expense at the U.S. federal statutory tax rate to the actual tax expense from continuing operations.
| Year Ended December 31, 2018
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Income tax expense, computed at the statutory rate of 21 percent | $ | 645 |  | $ | 288 |  | $ | 263 |  | $ | 174 |  | $ | 137 |  | $ | 46 |  | $ | 109 |  | $ | 35 |
State income tax, net of federal income tax effect | 30 |  | 14 |  | 13 |  | (17 | ) | 28 |  | 2 |  | 20 |  | 4 |
Amortization of excess deferred income tax | (61 | ) | — |  | (55 | ) | (1 | ) | (54 | ) | (3 | ) | (2 | ) | — |
AFUDC equity income | (42 | ) | (15 | ) | (22 | ) | (12 | ) | (10 | ) | (2 | ) | (2 | ) | — |
AFUDC equity depreciation | 31 |  | 18 |  | 9 |  | 5 |  | 4 |  | 1 |  | 4 |  | — |
Renewable energy production tax credits | (129 | ) | — |  | — |  | — |  | — |  | — |  | — |  | — |
Other tax credits | (28 | ) | (7 | ) | (13 | ) | (5 | ) | (8 | ) | (1 | ) | (1 | ) | (3 | )
Tax Act(a) | 20 |  | 1 |  | 25 |  | 19 |  | — |  | 2 |  | — |  | — |
Other items, net | (18 | ) | 4 |  | (2 | ) | (3 | ) | 4 |  | (2 | ) | — |  | 1 |
Income tax expense from continuing operations | $ | 448 |  | $ | 303 |  | $ | 218 |  | $ | 160 |  | $ | 101 |  | $ | 43 |  | $ | 128 |  | $ | 37 |
Effective tax rate | 14.6 | % | 22.1 | % | 17.4 | % | 19.3 | % | 15.4 | % | 19.6 | % | 24.6 | % | 22.3 | %
(a) | For the year ended December 31, 2018, the Company revised the December 31, 2017 estimates of the income tax effects of the Tax Act, in accordance with SAB 118. Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits.
| Year Ended December 31, 2017 |
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Income tax expense, computed at the statutory rate of 35 percent | $ | 1,493 |  | $ | 653 |  | $ | 536 |  | $ | 353 |  | $ | 265 |  | $ | 88 |  | $ | 229 |  | $ | 70 |
State income tax, net of federal income tax effect | 69 |  | 36 |  | 25 |  | 8 |  | 26 |  | (1 | ) | 23 |  | 3 |
AFUDC equity income | (81 | ) | (37 | ) | (32 | ) | (17 | ) | (16 | ) | (4 | ) | (8 | ) | — |
Renewable energy production tax credits | (132 | ) | — |  | — |  | — |  | — |  | — |  | — |  | — |
Tax Act(a) | (112 | ) | 15 |  | (246 | ) | (40 | ) | (226 | ) | (23 | ) | 55 |  | (12 | )
Tax true up | (52 | ) | (24 | ) | (19 | ) | (13 | ) | (7 | ) | (5 | ) | (6 | ) | — |
Other items, net | 11 |  | 9 |  | — |  | 1 |  | 4 |  | 4 |  | 8 |  | 1 |
Income tax expense from continuing operations | $ | 1,196 |  | $ | 652 |  | $ | 264 |  | $ | 292 |  | $ | 46 |  | $ | 59 |  | $ | 301 |  | $ | 62 |
Effective tax rate | 28.0 | % | 34.9 | % | 17.2 | % | 29.0 | % | 6.1 | % | 23.4 | % | 46.0 | % | 30.8 | %
(a) | Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related to abandoned or impaired assets, certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits.
| Year Ended December 31, 2016
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |
Income tax expense, computed at the statutory rate of 35 percent | $ | 1,307 |  | $ | 630 |  | $ | 548 |  | $ | 315 |  | $ | 306 |  | $ | 95 |  | $ | 212 |
State income tax, net of federal income tax effect | 64 |  | 46 |  | 20 |  | 10 |  | 30 |  | (2 | ) | 11 |
AFUDC equity income | (70 | ) | (36 | ) | (26 | ) | (17 | ) | (9 | ) | (2 | ) | (6 | )
Renewable energy production tax credits | (97 | ) | — |  | — |  | — |  | — |  | — |  | — |
Audit adjustment | 5 |  | 3 |  | — |  | — |  | — |  | — |  | — |
Tax true up | (14 | ) | (14 | ) | (11 | ) | (3 | ) | (9 | ) | (16 | ) | 2 |
Other items, net | (39 | ) | 5 |  | (4 | ) | (4 | ) | 4 |  | 3 |  | 6 |
Income tax expense from continuing operations | $ | 1,156 |  | $ | 634 |  | $ | 527 |  | $ | 301 |  | $ | 322 |  | $ | 78 |  | $ | 225 |
Effective tax rate | 31.0 | % | 35.2 | % | 33.7 | % | 33.4 | % | 36.9 | % | 28.9 | % | 37.1 | %
Schedule of Deferred Tax Assets and Liabilities |
| December 31, 2017
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Deferred credits and other liabilities | $ | 143 |  | $ | 33 |  | $ | 78 |  | $ | 23 |  | $ | 49 |  | $ | 11 |  | $ | 6 |  | $ | (5 | )
Capital lease obligations | 49 |  | 14 |  | — |  | — |  | — |  | — |  | 2 |  | — |
Pension, post-retirement and other employee benefits | 295 |  | (17 | ) | 111 |  | 44 |  | 60 |  | 14 |  | 18 |  | (4 | )
Progress Energy merger purchase accounting adjustments(a) | 536 |  | — |  | — |  | — |  | — |  | — |  | — |  | — |
Tax credits and NOL carryforwards | 4,527 |  | 234 |  | 402 |  | 156 |  | 143 |  | 25 |  | 216 |  | 70 |
Regulatory liabilities and deferred credits | — |  | 222 |  | — |  | — |  | — |  | 65 |  | — |  | 61 |
Investments and other assets | — |  | — |  | — |  | — |  | — |  | — |  | 1 |  | 18 |
Other | 73 |  | 10 |  | 1 |  | 4 |  | — |  | — |  | — |  | — |
Valuation allowance | (519 | ) | — |  | (14 | ) | — |  | — |  | — |  | — |  | — |
Total deferred income tax assets | 5,104 |  | 496 |  | 578 |  | 227 |  | 252 |  | 115 |  | 243 |  | 140 |
Investments and other assets | (1,419 | ) | (849 | ) | (470 | ) | (289 | ) | (187 | ) | — |  | (14 | ) | — |
Accelerated depreciation rates | (9,216 | ) | (3,060 | ) | (2,803 | ) | (1,583 | ) | (1,257 | ) | (896 | ) | (966 | ) | (697 | )
Regulatory assets and deferred debits, net | (1,090 | ) | — |  | (807 | ) | (238 | ) | (569 | ) | — |  | (188 | ) | — |
Other | — |  | — |  | — |  | — |  | — |  | — |  | — |  | (7 | )
Total deferred income tax liabilities | (11,725 | ) | (3,909 | ) | (4,080 | ) | (2,110 | ) | (2,013 | ) | (896 | ) | (1,168 | ) | (704 | )
Net deferred income tax liabilities | $ | (6,621 | ) | $ | (3,413 | ) | $ | (3,502 | ) | $ | (1,883 | ) | $ | (1,761 | ) | $ | (781 | ) | $ | (925 | ) | $ | (564 | )
(a) | Primarily related to capital lease obligations and debt fair value adjustments.
Net Deferred Income Tax Liability Components
| December 31, 2018
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Deferred credits and other liabilities | $ | 164 |  | $ | 64 |  | $ | 35 |  | $ | 53 |  | $ | — |  | $ | 17 |  | $ | 6 |  | $ | 17 |
Capital lease obligations | 60 |  | 26 |  | — |  | — |  | — |  | — |  | 2 |  | — |
Pension, post-retirement and other employee benefits | 347 |  | 24 |  | 110 |  | 47 |  | 58 |  | 16 |  | 24 |  | (1 | )
Progress Energy merger purchase accounting adjustments(a) | 483 |  | — |  | — |  | — |  | — |  | — |  | — |  | — |
Tax credits and NOL carryforwards | 4,580 |  | 257 |  | 693 |  | 215 |  | 363 |  | 42 |  | 237 |  | 110 |
Regulatory liabilities and deferred credits | — |  | — |  | — |  | — |  | — |  | 56 |  | — |  | 48 |
Investments and other assets | — |  | — |  | — |  | — |  | — |  | 18 |  | — |  | 16 |
Other | 25 |  | 6 |  | 5 |  | 5 |  | — |  | 1 |  | (1 | ) | — |
Valuation allowance | (484 | ) | — |  | — |  | — |  | — |  | — |  | — |  | — |
Total deferred income tax assets | 5,175 |  | 377 |  | 843 |  | 320 |  | 421 |  | 150 |  | 268 |  | 190 |
Investments and other assets | (1,317 | ) | (795 | ) | (430 | ) | (272 | ) | (163 | ) | — |  | (5 | ) | — |
Accelerated depreciation rates | (10,124 | ) | (3,207 | ) | (3,369 | ) | (1,735 | ) | (1,670 | ) | (967 | ) | (1,081 | ) | (733 | )
Regulatory assets and deferred debits, net | (1,540 | ) | (64 | ) | (985 | ) | (432 | ) | (574 | ) | — |  | (191 | ) | — |
Other | — |  | — |  | — |  | — |  | — |  | — |  | — |  | (8 | )
Total deferred income tax liabilities | (12,981 | ) | (4,066 | ) | (4,784 | ) | (2,439 | ) | (2,407 | ) | (967 | ) | (1,277 | ) | (741 | )
Net deferred income tax liabilities | $ | (7,806 | ) | $ | (3,689 | ) | $ | (3,941 | ) | $ | (2,119 | ) | $ | (1,986 | ) | $ | (817 | ) | $ | (1,009 | ) | $ | (551 | )
(a) | Primarily related to capital lease obligations and debt fair value adjustments.
Summary of Tax Credit Carryforwards | The following table presents the expiration of tax credits and NOL carryforwards.
| December 31, 2018
(in millions) | Amount |  |  | Expiration Year
Investment tax credits | $ | 1,614 |  |  | 2024 |  | — |  | 2038
Alternative minimum tax credits | 574 |  |  | Refundable by 2021
Federal NOL carryforwards(a)(e) | 788 |  |  | 2022 |  | — |  | Indefinite
State NOL carryforwards and credits(b)(e) | 301 |  |  | 2019 |  | — |  | Indefinite
Foreign NOL carryforwards(c) | 12 |  |  | 2027 |  | — |  | 2037
Foreign Tax Credits(d) | 1,271 |  |  | 2024 |  | — |  | 2027
Charitable contribution carryforwards | 20 |  |  | 2019 |  | — |  | 2023
Total tax credits and NOL carryforwards | $ | 4,580 |  |  |  |  |  |  |
(a) | A valuation allowance of $4 million has been recorded on the Federal NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table.
(b) | A valuation allowance of $85 million has been recorded on the state NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table.
(c) | A valuation allowance of $12 million has been recorded on the foreign NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table.
(d) | A valuation allowance of $383 million has been recorded on the foreign tax credits, as presented in the Net Deferred Income Tax Liability Components table.
(e) | Indefinite carryforward for Federal NOLs, and NOLs for states that have adopted the Tax Act's NOL provisions, generated in tax years beginning after December 31, 2017.
| December 31, 2017
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Deferred credits and other liabilities | $ | 143 |  | $ | 33 |  | $ | 78 |  | $ | 23 |  | $ | 49 |  | $ | 11 |  | $ | 6 |  | $ | (5 | )
Capital lease obligations | 49 |  | 14 |  | — |  | — |  | — |  | — |  | 2 |  | — |
Pension, post-retirement and other employee benefits | 295 |  | (17 | ) | 111 |  | 44 |  | 60 |  | 14 |  | 18 |  | (4 | )
Progress Energy merger purchase accounting adjustments(a) | 536 |  | — |  | — |  | — |  | — |  | — |  | — |  | — |
Tax credits and NOL carryforwards | 4,527 |  | 234 |  | 402 |  | 156 |  | 143 |  | 25 |  | 216 |  | 70 |
Regulatory liabilities and deferred credits | — |  | 222 |  | — |  | — |  | — |  | 65 |  | — |  | 61 |
Investments and other assets | — |  | — |  | — |  | — |  | — |  | — |  | 1 |  | 18 |
Other | 73 |  | 10 |  | 1 |  | 4 |  | — |  | — |  | — |  | — |
Valuation allowance | (519 | ) | — |  | (14 | ) | — |  | — |  | — |  | — |  | — |
Total deferred income tax assets | 5,104 |  | 496 |  | 578 |  | 227 |  | 252 |  | 115 |  | 243 |  | 140 |
Investments and other assets | (1,419 | ) | (849 | ) | (470 | ) | (289 | ) | (187 | ) | — |  | (14 | ) | — |
Accelerated depreciation rates | (9,216 | ) | (3,060 | ) | (2,803 | ) | (1,583 | ) | (1,257 | ) | (896 | ) | (966 | ) | (697 | )
Regulatory assets and deferred debits, net | (1,090 | ) | — |  | (807 | ) | (238 | ) | (569 | ) | — |  | (188 | ) | — |
Other | — |  | — |  | — |  | — |  | — |  | — |  | — |  | (7 | )
Total deferred income tax liabilities | (11,725 | ) | (3,909 | ) | (4,080 | ) | (2,110 | ) | (2,013 | ) | (896 | ) | (1,168 | ) | (704 | )
Net deferred income tax liabilities | $ | (6,621 | ) | $ | (3,413 | ) | $ | (3,502 | ) | $ | (1,883 | ) | $ | (1,761 | ) | $ | (781 | ) | $ | (925 | ) | $ | (564 | )
Schedule of Unrecognized Tax Benefits Roll Forward | The following tables present changes to unrecognized tax benefits.
| Year Ended December 31, 2018
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Unrecognized tax benefits – January 1 | $ | 25 |  | $ | 5 |  | $ | 5 |  | $ | 5 |  | $ | 5 |  | $ | 1 |  | $ | 1 |  | $ | 3 |
Unrecognized tax benefits increases (decreases) |  |  |  |  |  |  |  |
Gross decreases – tax positions in prior periods | (2 | ) | (1 | ) | — |  | — |  | (4 | ) | — |  | — |  | — |
Gross increases – current period tax positions | 7 |  | 2 |  | 4 |  | 1 |  | 2 |  | — |  | — |  | 1 |
Decreases due to settlements | (6 | ) | — |  | — |  | — |  | — |  | — |  | — |  | — |
Total changes | (1 | ) | 1 |  | 4 |  | 1 |  | (2 | ) | — |  | — |  | 1 |
Unrecognized tax benefits – December 31 | $ | 24 |  | $ | 6 |  | $ | 9 |  | $ | 6 |  | $ | 3 |  | $ | 1 |  | $ | 1 |  | $ | 4 |
| Year Ended December 31, 2017 |
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Unrecognized tax benefits – January 1 | $ | 17 |  | $ | 1 |  | $ | 2 |  | $ | 2 |  | $ | 4 |  | $ | 4 |  | $ | — |  | $ | — |
Unrecognized tax benefits increases (decreases) |  |  |  |  |  |  |  |
Gross increases – tax positions in prior periods | 12 |  | 4 |  | 3 |  | 3 |  | 1 |  | 1 |  | 1 |  | 3 |
Gross decreases – tax positions in prior periods | (4 | ) | — |  | — |  | — |  | — |  | (4 | ) | — |  | — |
Total changes | 8 |  | 4 |  | 3 |  | 3 |  | 1 |  | (3 | ) | 1 |  | 3 |
Unrecognized tax benefits – December 31 | $ | 25 |  | $ | 5 |  | $ | 5 |  | $ | 5 |  | $ | 5 |  | $ | 1 |  | $ | 1 |  | $ | 3 |
| Year Ended December 31, 2016
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |
Unrecognized tax benefits – January 1 | $ | 88 |  | $ | 72 |  | $ | 1 |  | $ | 3 |  | $ | — |  | $ | — |  | $ | 1 |
Unrecognized tax benefits increases (decreases) |  |  |  |  |  |  |
Gross increases – tax positions in prior periods | — |  | — |  | — |  | — |  | 4 |  | 4 |  | — |
Gross decreases – tax positions in prior periods | (4 | ) | (4 | ) | (1 | ) | (1 | ) | — |  | — |  | — |
Decreases due to settlements | (68 | ) | (67 | ) | — |  | — |  | — |  | — |  | (1 | )
Reduction due to lapse of statute of limitations | 1 |  | — |  | 2 |  | — |  | — |  | — |  | — |
Total changes | (71 | ) | (71 | ) | 1 |  | (1 | ) | 4 |  | 4 |  | (1 | )
Unrecognized tax benefits – December 31 | $ | 17 |  | $ | 1 |  | $ | 2 |  | $ | 2 |  | $ | 4 |  | $ | 4 |  | $ | — |
Summary of Income Tax Contingencies | The following table includes additional information regarding the Duke Energy Registrants' unrecognized tax benefits at December 31, 2018. All Duke Energy Registrants do not anticipate a material increase or decrease in unrecognized tax benefits within the next 12 months.
| December 31, 2018
|  | Duke |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont |
Amount that if recognized, would affect the effective tax rate or regulatory liability(a) | $ | 21 |  | $ | 6 |  | $ | 9 |  | $ | 6 |  | $ | 3 |  | $ | 1 |  | $ | 1 |  | $ | 4 |
Amount that if recognized, would be recorded as a component of discontinued operations | 2 |  | — |  | — |  | — |  | — |  | — |  | — |  | — |
(a) | Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana and Piedmont are unable to estimate the specific amounts that would affect the effective tax rate versus the regulatory liability.
The following tables include interest recognized in the Consolidated Statements of Operations and the Consolidated Balance Sheets.
| Year Ended December 31, 2018
|  |  | Duke |
| Duke |  | Progress |  | Energy |
(in millions) | Energy |  | Energy |  | Progress |
Net interest income recognized related to income taxes | $ | 2 |  | $ | — |  | $ | — |
Interest payable related to income taxes | 3 |  | 1 |  | 1 |
| Year Ended December 31, 2017
|  | Duke |  |  | Duke |  | Duke |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |
Net interest income recognized related to income taxes | $ | — |  | $ | — |  | $ | 1 |  | $ | — |  | $ | 1 |
Net interest expense recognized related to income taxes | — |  | 2 |  | — |  | — |  | — |
Interest payable related to income taxes | 5 |  | 25 |  | 1 |  | 1 |  | — |
| Year Ended December 31, 2016
|  | Duke |  |  | Duke |  | Duke |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |
Net interest income recognized related to income taxes | $ | — |  | $ | — |  | $ | 1 |  | $ | — |  | $ | 2 |
Net interest expense recognized related to income taxes | — |  | 7 |  | — |  | — |  | — |
Interest payable related to income taxes | 4 |  | 23 |  | 1 |  | 1 |  | — |
Piedmont Natural Gas [Member] |
Income Tax Disclosure [Line Items] |
Schedule of Components of Income Tax Expense (Benefit) |
| Piedmont
| Two Months Ended | Year Ended October 31,
(in millions) | December 31, 2016 | 2016
Current income taxes |  |
Federal | $ | 4 |  | $ | 27 |
State | (2 | ) | 12 |
Total current income taxes | 2 |  | 39 |
Deferred income taxes |  |
Federal | 24 |  | 79 |
State | 6 |  | 6 |
Total deferred income taxes(a) | 30 |  | 85 |
Total income tax expense from continuing operations included in Consolidated Statements of Operations | $ | 32 |  | $ | 124 |
(a) | Includes benefits of NOL and tax carryforwards of $17 million and $91 million for the two months ended December 31, 2016, and the year ended October 31, 2016, respectively.
Summary of Effective Tax Rates |
| Piedmont
| Two Months Ended | Year Ended October 31,
(in millions) | December 31, 2016 | 2016
Income tax expense, computed at the statutory rate of 35 percent | $ | 30 |  | $ | 111 |
State income tax, net of federal income tax effect | 1 |  | 11 |
Other items, net | 1 |  | 2 |
Income tax expense from continuing operations | $ | 32 |  | $ | 124 |
Effective tax rate | 37.2 | % | 39.1 | %

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