Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2011

Asset Retirement Obligations [Abstract]

Changes To Asset Retirement Obligations

December 31, 2011
	Duke Energy			Duke  Energy Carolinas			Duke Energy Ohio			Duke Energy Indiana
	(in millions)
Balance as of January 1,	$	1,816		$	1,728		$	27		$	46
Accretion expense(a)		111			105			2			2
Liabilities settled		(3	)		(1	)		(2	)		—
Revisions in estimates of cash flows		1			9			—			(9	)
Liabilities incurred in the current year		11			5			—			4
Balance as of December 31,	$	1,936		$	1,846		$	27		$	43

(a) 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.

	December 31, 2010
	Duke Energy			Duke  Energy Carolinas			Duke Energy Ohio			Duke Energy Indiana
	(in millions)
Balance as of January 1,	$	3,185		$	3,098		$	36		$	42
Accretion expense(a)		97			93			1			2
Correction of prior year error(b)		(1,465	)		(1,465	)		—			—
Liabilities settled		(10	)		(7	)		—			(3	)
Revisions in estimates of cash flows		(8	)		(1	)		(10	)		4
Liabilities incurred in the current year		12			5			—			1
Other		5			5			—			—
Balance as of December 31,	$	1,816		$	1,728		$	27		$	46

(a) 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.

(b) 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.