Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 77	$ 81	$ 98
Provision/adjustments	33	26	8
Cash reductions	(52)	(30)	(25)
Ending balance	58	77	81
Duke Energy Carolinas
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	11	10	10
Provision/adjustments	6	3	3
Cash reductions	(6)	(2)	(3)
Ending balance	11	11	10
Progress Energy
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	11	15	18
Provision/adjustments	9	2	3
Cash reductions	(4)	(6)	(6)
Ending balance	16	11	15
Duke Energy Progress
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	4	3	3
Provision/adjustments	2	3	2
Cash reductions	(2)	(2)	(2)
Ending balance	4	4	3
Duke Energy Florida
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	6	12	14
Provision/adjustments	5	(2)	2
Cash reductions	(2)	(4)	(4)
Ending balance	9	6	12
Duke Energy Ohio
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	48	47	59
Provision/adjustments	11	21	3
Cash reductions	(40)	(20)	(15)
Ending balance	19	48	47
Duke Energy Indiana
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5	5	10
Provision/adjustments		1	(4)
Cash reductions	(1)	(1)	(1)
Ending balance	4	5	5
Piedmont
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	2	2	1
Provision/adjustments	7	1	1
Cash reductions	(1)	(1)
Ending balance	8	$ 2	$ 2
Environmental reserves
Accrual for Environmental Loss Contingencies [Roll Forward]
Additional losses in excess of recorded reserves that could be incurred	59
Environmental reserves | Duke Energy Carolinas
Accrual for Environmental Loss Contingencies [Roll Forward]
Additional losses in excess of recorded reserves that could be incurred	11
Environmental reserves | Duke Energy Ohio
Accrual for Environmental Loss Contingencies [Roll Forward]
Additional losses in excess of recorded reserves that could be incurred	42
Environmental reserves | Piedmont
Accrual for Environmental Loss Contingencies [Roll Forward]
Additional losses in excess of recorded reserves that could be incurred	$ 2