Acquisitions and Sales of Other Assets (Accounting Charges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Significant Acquisitions and Disposals [Line Items]
Severance costs 1	$ 5	$ 146	$ 30	$ 146
FERC mitigation			0	117
Duke Energy Carolinas [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs 1	0	48	7	48
FERC mitigation			0	46
Progress Energy [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs 1	4	66	17	66
FERC mitigation			0	71
Duke Energy Progress [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs 1	3	42	12	42
FERC mitigation			0	71
Duke Energy Florida [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs 1	1	24	5	24
Duke Energy Ohio [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs 1	0	15	2	15
Duke Energy Indiana [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs 1	$ 0	$ 13	$ 2	$ 13