Commitments and Contingencies (Schedule of Environmental Loss Contingencies)(Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 79	$ 75	$ 61
Provision/adjustments	32	26	39
Cash reductions	(14)	(22)	(25)
Ending balance	97	79	75
Duke Energy Carolinas [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	11	12	12
Provision/adjustments	(1)		1
Cash reductions		(1)	(1)
Ending balance	10	11	12
Progress Energy [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	27	33	23
Provision/adjustments	1	4	19
Cash reductions	(11)	(10)	(9)
Ending balance	17	27	33
Duke Energy Progress [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	8	14	11
Provision/adjustments	4	(1)	5
Cash reductions	(7)	(5)	(2)
Ending balance	5	8	14
Duke Energy Florida [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	19	19	12
Provision/adjustments	(3)	5	14
Cash reductions	(4)	(5)	(7)
Ending balance	12	19	19
Duke Energy Ohio [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	27	15	28
Provision/adjustments	28	20	5
Cash reductions	(1)	(8)	(18)
Ending balance	54	27	15
Duke Energy Indiana [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	7	8	9
Provision/adjustments	4	1	3
Cash reductions	(1)	(2)	(4)
Ending balance	$ 10	$ 7	$ 8