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Income Taxes (Other Disclosures) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Oct. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | $ 25 | $ 17 | $ 88 |
Gross increases-tax positions in prior periods |  | 12 |  |
Gross decreases-tax positions in prior periods | (2) | (4) | (4) |
Gross increases-current period tax positions | 7 |  |  |
Decreases due to settlements | (6) |  | (68) |
Reduction due to lapse of statute of limitations |  |  | 1 |
Total changes | (1) | 8 | (71) |
Unrecognized Tax Benefits - December 31 | 24 | 25 | 17 |
Amount that if recognized, would affect the effective tax rate or regulatory liability | 21 |  |  |
Amount that if recognized, would be recorded as a component of discontinued operations | 2 |  |  |
Income Tax Examination, Penalties and Interest Expense [Abstract] |  |  |  |
Net interest income recognized related to income taxes | 2 |  |  |
Income Tax Examination, Penalties and Interest Accrued [Abstract] |  |  |  |
Interest payable related to income taxes | 3 | 5 | 4 |
Duke Energy Carolinas [Member] |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | 5 | 1 | 72 |
Gross increases-tax positions in prior periods |  | 4 |  |
Gross decreases-tax positions in prior periods | (1) |  | (4) |
Gross increases-current period tax positions | 2 |  |  |
Decreases due to settlements |  |  | (67) |
Total changes | 1 | 4 | (71) |
Unrecognized Tax Benefits - December 31 | 6 | 5 | 1 |
Amount that if recognized, would affect the effective tax rate or regulatory liability | 6 |  |  |
Income Tax Examination, Penalties and Interest Expense [Abstract] |  |  |  |
Net interest expense recognized related to income taxes |  | 2 | 7 |
Income Tax Examination, Penalties and Interest Accrued [Abstract] |  |  |  |
Interest payable related to income taxes |  | 25 | 23 |
Progress Energy [Member] |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | 5 | 2 | 1 |
Gross increases-tax positions in prior periods |  | 3 |  |
Gross decreases-tax positions in prior periods |  |  | (1) |
Gross increases-current period tax positions | 4 |  |  |
Reduction due to lapse of statute of limitations |  |  | 2 |
Total changes | 4 | 3 | 1 |
Unrecognized Tax Benefits - December 31 | 9 | 5 | 2 |
Amount that if recognized, would affect the effective tax rate or regulatory liability | 9 |  |  |
Income Tax Examination, Penalties and Interest Expense [Abstract] |  |  |  |
Net interest income recognized related to income taxes |  | 1 | 1 |
Income Tax Examination, Penalties and Interest Accrued [Abstract] |  |  |  |
Interest payable related to income taxes | 1 | 1 | 1 |
Duke Energy Progress [Member] |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | 5 | 2 | 3 |
Gross increases-tax positions in prior periods |  | 3 |  |
Gross decreases-tax positions in prior periods |  |  | (1) |
Gross increases-current period tax positions | 1 |  |  |
Total changes | 1 | 3 | (1) |
Unrecognized Tax Benefits - December 31 | 6 | 5 | 2 |
Amount that if recognized, would affect the effective tax rate or regulatory liability | 6 |  |  |
Income Tax Examination, Penalties and Interest Accrued [Abstract] |  |  |  |
Interest payable related to income taxes | 1 | 1 | 1 |
Duke Energy Florida [Member] |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | 5 | 4 |  |
Gross increases-tax positions in prior periods |  | 1 | 4 |
Gross decreases-tax positions in prior periods | (4) |  |  |
Gross increases-current period tax positions | 2 |  |  |
Total changes | (2) | 1 | 4 |
Unrecognized Tax Benefits - December 31 | 3 | 5 | 4 |
Amount that if recognized, would affect the effective tax rate or regulatory liability | 3 |  |  |
Income Tax Examination, Penalties and Interest Expense [Abstract] |  |  |  |
Net interest income recognized related to income taxes |  | 1 | 2 |
Duke Energy Ohio [Member] |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | 1 | 4 |  |
Gross increases-tax positions in prior periods |  | 1 | 4 |
Gross decreases-tax positions in prior periods |  | (4) |  |
Total changes |  | (3) | 4 |
Unrecognized Tax Benefits - December 31 | 1 | 1 | 4 |
Amount that if recognized, would affect the effective tax rate or regulatory liability | 1 |  |  |
Duke Energy Indiana [Member] |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | 1 |  | 1 |
Gross increases-tax positions in prior periods |  | 1 |  |
Decreases due to settlements |  |  | (1) |
Total changes |  | 1 | $ (1) |
Unrecognized Tax Benefits - December 31 | 1 | 1 |  |
Amount that if recognized, would affect the effective tax rate or regulatory liability | 1 |  |  |
Piedmont Natural Gas [Member] |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Unrecognized Tax Benefits - January 1 | 3 |  |  |
Gross increases-tax positions in prior periods |  | 3 |  |
Gross increases-current period tax positions | 1 |  |  |
Total changes | 1 | 3 |  |
Unrecognized Tax Benefits - December 31 | 4 | $ 3 |  |
Amount that if recognized, would affect the effective tax rate or regulatory liability | $ 4 |  |  |
Income Tax Examination, Penalties and Interest Expense [Abstract] |  |  |  |
Net interest income recognized related to income taxes |  |  |  | $ 1

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