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