Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	$ 89
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	97	$ 79
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	5	9
Cash reductions	(4)	(6)
Ending balance	98	82
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
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	0	(1)
Ending balance	10	10
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
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	2	4
Cash reductions	(2)	(4)
Ending balance	17	27
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
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	0	3
Cash reductions	(1)	(2)
Ending balance	4	9
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
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	2	1
Cash reductions	(1)	(2)
Ending balance	13	18
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
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	1	5
Cash reductions	(1)	(1)
Ending balance	54	31
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
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	3
Cash reductions	(1)
Ending balance	$ 12	$ 7