Asset Retirement Obligations (Changes To Asset Retirement Obligations) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010
Asset Retirement Obligations [Abstract]
Balance as of January 1	$ 1,816		$ 3,185
Accretion expense	111	[1]	97	[2]
Correction of prior year error			(1,465)	[3]
Liabilities settled	(3)		(10)
Revisions in estimates of cash flows	1		(8)
Liabilities incurred in the current year	11		12
Other			5
Balance as of December 31	$ 1,936		$ 1,816

[1] Substantially all of the accretion expense for the years ended December 31, 2011 relate to Duke Energy's regulated electric operations and has been deferred in accordance with regulatory accounting treatment, as discussed above.

[2] Substantially all of the accretion expense for the years ended December 31, 2010 relate to Duke Energy's regulated electric operations and has been deferred in accordance with regulatory accounting treatment, as discussed above.

[3] In the second quarter of 2010, Duke Energy Carolinas recorded a $1.5 billion correction of an error to reduce the nuclear decommissioning asset retirement obligation liability, with offsetting impacts to regulatory assets and property, plant and equipment. This correction had no impact on Duke Energy Carolinas' equity, results of operations or cash flows.