Leases (Rent Expense) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
Rental expense on operating leases	$ 268
Duke Energy Carolinas
Operating Leased Assets [Line Items]
Rental expense on operating leases	49
Progress Energy
Operating Leased Assets [Line Items]
Rental expense on operating leases	143
Duke Energy Progress
Operating Leased Assets [Line Items]
Rental expense on operating leases	75
Duke Energy Florida
Operating Leased Assets [Line Items]
Rental expense on operating leases	68
Duke Energy Ohio
Operating Leased Assets [Line Items]
Rental expense on operating leases	13
Duke Energy Indiana
Operating Leased Assets [Line Items]
Rental expense on operating leases	21
Piedmont
Operating Leased Assets [Line Items]
Rental expense on operating leases	$ 11