Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	$ 89
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	97	79
Provisions/Adjustments	2	3
Cash reductions	(3)	(1)
Ending balance	96	81
Duke Energy Carolinas [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	25
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	10		11
Ending balance	10	11	11
Progress Energy [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	15
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	17	27
Provisions/Adjustments		3
Cash reductions		(1)
Ending balance	17	29
Duke Energy Progress [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	1
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5	8
Provisions/Adjustments		2
Ending balance	5	10
Duke Energy Florida [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	14
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	12	19
Provisions/Adjustments		1
Cash reductions		(1)
Ending balance	12	19
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		27
Provisions/Adjustments	1
Cash reductions	(1)
Ending balance	54	27	27
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	10		7
Provisions/Adjustments	2
Cash reductions	(1)
Ending balance	$ 11	$ 7	$ 7