Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 41		$ 39		$ 125		$ 84
Interest cost on benefit obligation	80		94		240		214
Expected return on plan assets	(137)		(142)		(411)		(330)
Amortization of actuarial loss (gain)	61		47		183		96
Amortization of prior service cost (credit)	(2)		3		(8)		6
Other	2		2		5		4
Net periodic costs	45	[1]	43	[1]	134	[2]	74	[2]
Regulatory asset amortization	3		3		9		10
Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1				2		1
Interest cost on benefit obligation	3		5		10		8
Amortization of actuarial loss (gain)	1		1		4		2
Amortization of prior service cost (credit)					(1)		1
Net periodic costs	5		6		15		12
Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	7		7		21		10
Interest cost on benefit obligation	19		19		55		36
Expected return on plan assets	(4)		(4)		(11)		(12)
Amortization of net transition liability			3				7
Amortization of actuarial loss (gain)	13		8		39		5
Amortization of prior service cost (credit)	(3)		(2)		(9)		(6)
Special termination charges			9				9
Net periodic costs	32	[3]	40	[3]	95	[4]	49	[4]
Regulatory asset amortization	2		3		6		7
Duke Energy Carolinas [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	12		9		37		26
Interest cost on benefit obligation	20		23		60		68
Expected return on plan assets	(37)		(36)		(111)		(109)
Amortization of actuarial loss (gain)	15		11		45		34
Amortization of prior service cost (credit)	(2)				(5)		1
Other	1				2		1
Net periodic costs	9		7		28		21
Duke Energy Carolinas [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on benefit obligation					1		1
Net periodic costs					1		1
Duke Energy Carolinas [Member] | Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1		1		2		2
Interest cost on benefit obligation	3		4		9		12
Expected return on plan assets	(2)		(3)		(7)		(8)
Amortization of net transition liability			2				5
Amortization of actuarial loss (gain)			1		2		2
Amortization of prior service cost (credit)	(2)		(2)		(6)		(4)
Special termination charges			1				1
Net periodic costs	0		4		0		10
Progress Energy [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	15		16		45		47
Interest cost on benefit obligation	29		32		87		95
Expected return on plan assets	(50)		(48)		(149)		(141)
Amortization of actuarial loss (gain)	26		24		76		69
Amortization of prior service cost (credit)	(1)		2		(3)		7
Other			1		1		1
Net periodic costs	19		27		57		78
Progress Energy [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1				1		1
Interest cost on benefit obligation	1		2		5		6
Amortization of actuarial loss (gain)	1		1		3		3
Amortization of prior service cost (credit)					(1)
Net periodic costs	3		3		8		10
Progress Energy [Member] | Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6		5		17		12
Interest cost on benefit obligation	12		11		35		32
Expected return on plan assets							(1)
Amortization of net transition liability			1				3
Amortization of actuarial loss (gain)	13		10		42		25
Amortization of prior service cost (credit)					(1)
Special termination charges			5				5
Net periodic costs	31		32		93		76
Duke Energy Progress [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6		6		17		19
Interest cost on benefit obligation	13		15		38		43
Expected return on plan assets	(24)		(25)		(71)		(72)
Amortization of actuarial loss (gain)	11		9		34		28
Amortization of prior service cost (credit)	(1)		2		(1)		6
Other	1		1		1		1
Net periodic costs	6		8		18		25
Duke Energy Progress [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1				1		1
Interest cost on benefit obligation			1		1		1
Amortization of actuarial loss (gain)	1				1		1
Net periodic costs	2		1		3		3
Duke Energy Progress [Member] | Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3		2		9		6
Interest cost on benefit obligation	7		6		19		17
Amortization of actuarial loss (gain)	8		6		26		14
Amortization of prior service cost (credit)					(1)
Special termination charges			2				2
Net periodic costs	18		16		53		39
Duke Energy Florida [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	8		8		23		22
Interest cost on benefit obligation	13		14		40		42
Expected return on plan assets	(21)		(21)		(65)		(61)
Amortization of actuarial loss (gain)	12		13		37		36
Amortization of prior service cost (credit)	(1)				(2)
Net periodic costs	11		14		33		39
Duke Energy Florida [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on benefit obligation			1		1		2
Amortization of actuarial loss (gain)	1				1
Net periodic costs	1		1		2		2
Duke Energy Florida [Member] | Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2		2		6		5
Interest cost on benefit obligation	5		4		13		13
Expected return on plan assets							(1)
Amortization of net transition liability			1				2
Amortization of actuarial loss (gain)	4		3		12		9
Special termination charges			1				1
Net periodic costs	11		11		31		29
Duke Energy Ohio [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1		2		4		5
Interest cost on benefit obligation	5		7		16		23
Expected return on plan assets	(7)		(11)		(22)		(33)
Amortization of actuarial loss (gain)	3		2		9		7
Net periodic costs	2	[5]	0	[5]	7	[6]	2	[6]
Regulatory asset amortization	1		2		4		5
Duke Energy Ohio [Member] | Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost			1				1
Interest cost on benefit obligation			1		1		2
Expected return on plan assets			(1)				(1)
Amortization of actuarial loss (gain)			(1)		(1)		(2)
Net periodic costs			0		0	[7]	0	[7]
Regulatory asset amortization					1		1
Duke Energy Indiana [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2		2		8		7
Interest cost on benefit obligation	7		8		21		23
Expected return on plan assets	(11)		(12)		(33)		(35)
Amortization of actuarial loss (gain)	6		3		17		10
Amortization of prior service cost (credit)			1				2
Other	1				1
Net periodic costs	5		2		14		7
Duke Energy Indiana [Member] | Other Post-Retirement Benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1		1		1		1
Interest cost on benefit obligation	1		1		4		5
Expected return on plan assets	(1)				(1)		(1)
Amortization of actuarial loss (gain)	1				1		(1)
Amortization of prior service cost (credit)							1
Net periodic costs	$ 2		$ 2		$ 5		$ 5

[1] Duke Energy amounts exclude $3 million for each of the three months ended September 30, 2013 and 2012, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[2] Duke Energy amounts exclude $9 million and $10 million for the nine months ended September 30, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[3] Duke Energy amounts exclude $2 million and $3 million for the three months ended September 30, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[4] Duke Energy amounts exclude $6 million and $7 million for the nine months ended September 30, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[5] Duke Energy Ohio amounts exclude $1 million and $2 million for the three months ended September 30, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[6] Duke Energy Ohio amounts exclude $4 million and $5 million for the nine months ended September 30, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[7] Duke Energy Ohio amounts exclude $1 million for each of the nine months ended September 30, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.