Employee Benefit Plans (Summary of Accumulated Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	$ 11,741		$ 4,046
Regulatory liabilities	5,740		3,006
Accumulated other comprehensive loss	(306)		(234)
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	1,948		2,066
Regulatory liabilities	2,180		1,990
Accumulated other comprehensive loss	(16)		(19)
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	5,548		3,699
Regulatory liabilities	2,497		2,775
Accumulated other comprehensive loss	(67)		(165)
Progress Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	1,922		1,713
Regulatory liabilities	1,548		1,545
Accumulated other comprehensive loss	0		(71)
Progress Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	3,500		1,873
Regulatory liabilities	805		1,070
Accumulated other comprehensive loss	0		(27)
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	625		548
Regulatory liabilities	293		295
Accumulated other comprehensive loss	(1)		(28)
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	936		912
Regulatory liabilities	752		686
Accumulated other comprehensive loss	5		7
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	14		(10)
Prior service credit	(7)
Actuarial gain/loss arising during the year	(2)		60
Net amount recognized in accumulated other comprehensive (income)/loss	(29)		49
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	0		0
Actuarial gain/loss arising during the year	0		0
Net amount recognized in accumulated other comprehensive (income)/loss	0		0
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	0		24
Actuarial gain/loss arising during the year	3		13
Net amount recognized in accumulated other comprehensive (income)/loss	0		(38)
Qualified Pension Plans [Member] | Progress Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	0		0
Actuarial gain/loss arising during the year	0		0
Net amount recognized in accumulated other comprehensive (income)/loss	0		0
Qualified Pension Plans [Member] | Progress Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	0		0
Actuarial gain/loss arising during the year	0		0
Net amount recognized in accumulated other comprehensive (income)/loss	0		0
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	15		1
Actuarial gain/loss arising during the year			10
Net amount recognized in accumulated other comprehensive (income)/loss	(38)		8
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	0		0
Actuarial gain/loss arising during the year	0		0
Net amount recognized in accumulated other comprehensive (income)/loss	0		0
Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	2,387		1,411
Deferred income tax asset	(59)		(73)
Prior service credit	(4)		4
Actuarial gain/loss arising during the year	166		201
Net amount recognized in accumulated other comprehensive (income)/loss	103	[1]	132	[2]
Accumulated other comprehensive loss	9		19
Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	582		693
Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	1,079		1,155
Deferred income tax asset	(9)		(9)
Prior service credit			1
Actuarial gain/loss arising during the year	26		25
Net amount recognized in accumulated other comprehensive (income)/loss	17		17
Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	472		561
Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	541		518
Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	144		122
Deferred income tax asset			(15)
Prior service credit			1
Actuarial gain/loss arising during the year			52
Net amount recognized in accumulated other comprehensive (income)/loss			38
Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	246		229
Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset			(1)
Actuarial gain/loss arising during the year	(2)		1
Net amount recognized in accumulated other comprehensive (income)/loss	(2)
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax asset	(1)		5
Actuarial gain/loss arising during the year	3		7
Net amount recognized in accumulated other comprehensive (income)/loss	2		(8)
Non-Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	59		25
Regulatory liabilities	2		10
Actuarial gain/loss arising during the year	(1)		1
Net amount recognized in accumulated other comprehensive (income)/loss	(1)		1
Non-Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	3		3
Non-Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	34		40
Deferred income tax asset	(4)		(3)
Actuarial gain/loss arising during the year	12		9
Net amount recognized in accumulated other comprehensive (income)/loss	8		6
Non-Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	7		9
Non-Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	9		8
Non-Qualified Pension Plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	2		2
Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax liability	2		(1)
Net amount recognized in accumulated other comprehensive (income)/loss	2		2
Other Post-Retirement Benefit plans [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax liability			2
Actuarial gain/loss arising during the year			2
Net amount recognized in accumulated other comprehensive (income)/loss			4
Other Post-Retirement Benefit plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred income tax liability	4		1
Prior service credit	1
Actuarial gain/loss arising during the year	2		2
Net amount recognized in accumulated other comprehensive (income)/loss	6		2
Other Post-Retirement Benefit plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	521		37
Regulatory liabilities	101		107
Deferred income tax liability	2		4
Prior service credit	(3)		(3)
Actuarial gain/loss arising during the year	2		6
Net amount recognized in accumulated other comprehensive (income)/loss	(3)		(5)
Other Post-Retirement Benefit plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	17		37
Other Post-Retirement Benefit plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	505		277
Other Post-Retirement Benefit plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	291		121
Other Post-Retirement Benefit plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Progress Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	170		142
Other Post-Retirement Benefit plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory liabilities	18		19
Deferred income tax liability			4
Prior service credit			(1)
Actuarial gain/loss arising during the year			9
Net amount recognized in accumulated other comprehensive (income)/loss			(6)
Other Post-Retirement Benefit plans [Member] | Regulatory Assets And Deferred Debits And AOCI [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets	77		83
Regulatory liabilities	$ 68		$ 70

[1] Duke Energy amount includes $30 million and $17 million recognized in Other within Current Liabilities on the Consolidated Balance Sheets as of December 31, 2012 and 2011, respectively.

[2] Excludes accumulated other comprehensive income of $9 million and $19 million as of December 31, 2012 and 2011, respectively, net of tax, associated with a Brazilian retirement plan.