Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	$ 317	$ 487
Accumulated amortization	(54)	(109)
Total intangible assets, net	263	378
Amortization expense	6	13	14
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2015	11
2016	8
2017	7
2018	7
2019	7
Pretax impairment charge	81	399	666
Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	23	63
Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	97	82
Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	180
Accumulated amortization	(15)	(73)
Wind Development Rights [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	97	86
Accumulated amortization	(14)	(12)
Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	76	76
Accumulated amortization	(25)	(24)
Duke Energy Carolinas [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	26	17
Total intangible assets, net	26	17
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Pretax impairment charge	3		31
Duke Energy Carolinas [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	1	1
Duke Energy Carolinas [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	25	16
Progress Energy [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	76	85
Total intangible assets, net	76	85
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Pretax impairment charge	(16)	380	200
Progress Energy [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	7	21
Progress Energy [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	69	64
Duke Energy Progress [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	72	67
Total intangible assets, net	72	67
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Pretax impairment charge	(18)	22	54
Duke Energy Progress [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Duke Energy Progress [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	69	64
Duke Energy Florida [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	4	18
Total intangible assets, net	4	18
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Pretax impairment charge	2	358	146
Duke Energy Florida [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	4	18
Duke Energy Ohio [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	178
Accumulated amortization		(60)
Total intangible assets, net	3	118
Amortization expense	2	8	12
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2015	2
2016	1
2017	1
2018	1
2019	1
Pretax impairment charge	94	5	2
Duke Energy Ohio [Member] | Other VIEs [Member]
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Pretax impairment charge	94
Duke Energy Ohio [Member] | Commercial Power [Member] | Other VIEs [Member]
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Pretax impairment charge	94
Duke Energy Ohio [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount		20
Duke Energy Ohio [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	2
Duke Energy Ohio [Member] | Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount		156
Accumulated amortization		(60)
Duke Energy Indiana [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	40	45
Accumulated amortization	(15)	(13)
Total intangible assets, net	25	32
Amortization expense	1	1	1
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2015	5
2016	3
2017	2
2018	2
2019	2
Pretax impairment charge	0	0	579
Duke Energy Indiana [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	16	21
Duke Energy Indiana [Member] | Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	$ (15)	$ (13)