Revenue (Unbilled Revenues) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	$ 788	$ 843
Duke Energy Carolinas
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	284	298
Progress Energy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	274	217
Duke Energy Progress
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	139	122
Duke Energy Florida
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	135	95
Duke Energy Ohio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	1	1
Duke Energy Ohio | CRC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	66	82
Duke Energy Indiana
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	16	16
Duke Energy Indiana | CRC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	106	115
Piedmont Natural Gas
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled Receivables	$ 5	$ 78