Revenue (Unbilled Revenues) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 969	$ 843
Duke Energy Carolinas
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	328	298
Progress Energy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	283	217
Duke Energy Progress
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	167	122
Duke Energy Florida
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	116	95
Duke Energy Ohio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	2	1
Duke Energy Ohio | CRC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	87	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	134	115
Piedmont
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 86	$ 78