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Commitments and Contingencies (Schedule of Legal Reserves) (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Legal Reserves Details [Line Items] |  |
Reserves for Legal Matters | $ 68 | $ 62
Duke Energy Carolinas |  |
Legal Reserves Details [Line Items] |  |
Reserves for Legal Matters | 2 | 2
Progress Energy |  |
Legal Reserves Details [Line Items] |  |
Reserves for Legal Matters | 61 | 55
Duke Energy Progress |  |
Legal Reserves Details [Line Items] |  |
Reserves for Legal Matters | 13 | 12
Duke Energy Florida |  |
Legal Reserves Details [Line Items] |  |
Reserves for Legal Matters | 28 | 22
Piedmont |  |
Legal Reserves Details [Line Items] |  |
Reserves for Legal Matters | $ 1 | $ 1

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- Definition Amount of loss contingency liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 + Details
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