Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	$ 69
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	97	$ 97
Provisions/adjustments	34	4
Cash reductions	(12)	(4)
Ending balance	119	97
Duke Energy Carolinas [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	22
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	10	10
Provisions/adjustments	5
Cash reductions	(4)
Ending balance	11	10
Progress Energy [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	17	17
Provisions/adjustments	5	3
Cash reductions	(6)	(2)
Ending balance	16	18
Duke Energy Progress [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	3	5
Provisions/adjustments	2
Cash reductions	(2)	(1)
Ending balance	3	4
Duke Energy Florida [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	14	12
Provisions/adjustments	3	3
Cash reductions	(4)	(1)
Ending balance	13	14
Duke Energy Ohio [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	36
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	54	54
Provisions/adjustments	6	1
Cash reductions	(1)	(1)
Ending balance	59	54
Duke Energy Indiana [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	7
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	12	10
Provisions/adjustments	20	3
Cash reductions	(2)	(1)
Ending balance	$ 30	$ 12