Debt and Credit Facilities (Narrative) (Details) - Revolving Credit Facility [Member]	Mar. 31, 2019 USD ($)
Debt Instrument [Line Items]
Facility size	$ 8,000,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Facility size	1,750,000,000
Duke Energy Carolinas [Member] | USDOJ [Member] | North Carolina Ash Basins [Member]
Debt Instrument [Line Items]
Minimum master credit facility balance required	250,000,000
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Facility size	1,400,000,000
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Facility size	$ 500,000,000