Revenue (Unbilled Revenues) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 843	$ 896
Duke Energy Carolinas
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	298	313
Progress Energy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	217	244
Duke Energy Progress
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	122	148
Duke Energy Florida
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	95	96
Duke Energy Ohio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	1	2
Duke Energy Ohio | CRC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	82	86
Duke Energy Indiana
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	16	23
Duke Energy Indiana | CRC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	115	128
Piedmont
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 78	$ 73