Regulatory Matters (Schedule of MISO Exit fees)(Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Restructuring Reserve [Roll Forward]
Balance at December 31, 2012	$ 135
Restructuring reserve, period expense	(35)	[1]
Balance at June 30, 2013	80
Duke Energy Ohio [Member] | RTO Realignment [Member]
Restructuring Reserve [Roll Forward]
Balance at December 31, 2012	97
Cash reductions	(2)
Provision/adjustments	2
Balance at June 30, 2013	$ 97	[2]

[1] Provision / Adjustments for Duke Energy, Progress Energy and Duke Energy Florida includes $28 million of severance costs deferred related to Crystal River Unit 3.

[2] As of June 30, 2013, $70 million is recorded as a Regulatory asset on Duke Energy Ohio's Condensed Consolidated Balance Sheets.