Acquisitions and Sales of Other Assets (Accounting Charges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013		Jun. 30, 2013
Significant Acquisitions and Disposals [Line Items]
Severance costs	$ 9	[1]	$ 25	[1]
Duke Energy Carolinas [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs	2		7
Progress Energy [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs	6		13
Duke Energy Progress [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs	4		9
Duke Energy Florida [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs	2		4
Duke Energy Ohio [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs	1		2
Duke Energy Indiana [Member]
Significant Acquisitions and Disposals [Line Items]
Severance costs	$ 1		$ 2

[1] Includes $5 million of accelerated stock award expense for the six months ended June 30, 2013. There was an insignificant amount of accelerated stock award expense for the three months ended June 30, 2013.