Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Summary Of Significant Accounting Policies [Abstract]

Restricted Cash

	December 31,
	2011		2010
	(in millions)
Duke Energy	$	104	$	126
Duke Energy Carolinas		—		2
Duke Energy Ohio		30		4
Duke Energy Indiana		—		6

Components Of Inventory

	December 31, 2011
	Duke Energy		Duke  Energy Carolinas		Duke Energy Ohio		Duke Energy Indiana
	(in millions)
Materials and supplies	$	873	$	505	$	150	$	134
Coal held for electric generation		712		412		90		196
Natural gas		3		—		3		—
Total Inventory	$	1,588	$	917	$	243	$	330

	December 31, 2010
	Duke Energy		Duke Energy Carolinas		Duke Energy Ohio		Duke Energy Indiana
	(in millions)
Materials and supplies	$	734	$	476	$	106	$	78
Coal held for electric generation		528		240		92		189
Natural gas		56		—		56		—
Total Inventory	$	1,318	$	716	$	254	$	267

Schedule Of Composite Weighted-Average Depreciation Rates

	December 31,
	2011			2010			2009
Duke Energy(a)		3.2	%		3.2	%		3.3	%
Duke Energy Carolinas(a)		2.6	%		2.7	%		2.0	%
Duke Energy Ohio		3.5	%		4.1	%		3.8	%
Duke Energy Indiana		3.4	%		3.5	%		4.2	%

(a) Excludes nuclear fuel.

Summary Of Excise Taxes

	Year Ended December 31,
	2011		2010		2009
	(in millions)
Duke Energy Carolinas	$	153	$	156	$	132
Duke Energy Ohio		109		115		117
Duke Energy Indiana		31		29		27
Total Duke Energy	$	293	$	300	$	276

Schedule of Unbilled Revenues With Restricted Receivables

	December 31, 2011		December 31, 2010
	(in millions)
Duke Energy	$	674	$	751
Duke Energy Carolinas		293		322
Duke Energy Ohio(a)		50		54
Duke Energy Indiana		2		12