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Business Segments (Narrative) (Details)
$ in Millions
3 Months Ended
Mar. 31, 2021
USD ($)
segment
Duke Energy Ohio  
Segment Reporting Information [Line Items]  
Number of reportable segments | segment 2
Wind and solar | Nonregulated  
Segment Reporting Information [Line Items]  
Renewable merchant plants | $ $ 210
Joint owner ownership percentage 51.00%