Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	$ 58
Provisions/adjustments	3
Cash reductions	(3)
Balance at end of period	58
Environmental exit costs, reasonably possible additional loss	58
Duke Energy Carolinas
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	11
Cash reductions	(1)
Balance at end of period	10
Environmental exit costs, reasonably possible additional loss	11
Progress Energy
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	16
Cash reductions	(1)
Balance at end of period	15
Duke Energy Progress
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	4
Provisions/adjustments	1
Cash reductions	0
Balance at end of period	5
Duke Energy Florida
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	9
Cash reductions	0
Balance at end of period	9
Duke Energy Ohio
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	19
Provisions/adjustments	1
Cash reductions	(1)
Balance at end of period	19
Environmental exit costs, reasonably possible additional loss	41
Duke Energy Indiana
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	4
Provisions/adjustments	1
Cash reductions	0
Balance at end of period	5
Piedmont Natural Gas
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of period	8
Cash reductions	0
Balance at end of period	8
Environmental exit costs, reasonably possible additional loss	$ 2