Acquisitions and Sales of Other Assets (Accounting Charges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Significant Acquisitions and Disposals [Line Items]
Severance Costs	$ 16	[1]
Duke Energy Carolinas [Member]
Significant Acquisitions and Disposals [Line Items]
Severance Costs	5
Progress Energy [Member]
Significant Acquisitions and Disposals [Line Items]
Severance Costs	7
Duke Energy Progress [Member]
Significant Acquisitions and Disposals [Line Items]
Severance Costs	5
Duke Energy Florida [Member]
Significant Acquisitions and Disposals [Line Items]
Severance Costs	2
Duke Energy Ohio [Member]
Significant Acquisitions and Disposals [Line Items]
Severance Costs	1
Duke Energy Indiana [Member]
Significant Acquisitions and Disposals [Line Items]
Severance Costs	$ 2

[1] Includes $5 million of accelerated stock award expense.