Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	$ 83
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	97	$ 97
Provisions/adjustments	10	2
Cash reductions	(3)	(3)
Ending balance	104	96
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	2
Cash reductions	(1)
Ending balance	11	10
Progress Energy [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	17	17
Provisions/adjustments	1
Cash reductions	(2)
Ending balance	16	17
Duke Energy Progress [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	3	5
Provisions/adjustments	0
Cash reductions	(1)
Ending balance	2	5
Duke Energy Florida [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	14	12
Provisions/adjustments	1
Cash reductions	(1)
Ending balance	14	12
Duke Energy Ohio [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	42
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	54	54
Provisions/adjustments		1
Cash reductions	0	(1)
Ending balance	54	54
Duke Energy Indiana [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	15
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	12	10
Provisions/adjustments	6	2
Cash reductions	0	(1)
Ending balance	$ 18	$ 11