Employee Benefit Plans (Components Of Net Periodic Pension Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 42		$ 23
Interest cost on benefit obligation	80		61
Expected return on plan assets	(137)		(94)
Amortization of prior service cost (credit)	(3)		1
Amortization of actuarial loss (gain)	61		24
Other	2		1
Net periodic costs	45	[1]	16	[1]
Regulatory asset amortization	3		3
Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7		2
Interest cost on benefit obligation	18		8
Expected return on plan assets	(3)		(4)
Amortization of prior service cost (credit)	(3)		(2)
Amortization of net transition liability			2
Amortization of actuarial loss (gain)	13		(2)
Net periodic costs	32	[2]	4	[2]
Regulatory asset amortization	2		2
Duke Energy Carolinas [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	12		9
Interest cost on benefit obligation	20		23
Expected return on plan assets	(37)		(36)
Amortization of prior service cost (credit)	(2)		0
Amortization of actuarial loss (gain)	15		11
Other	1		0
Net periodic costs	9		7
Duke Energy Carolinas [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1		1
Interest cost on benefit obligation	3		4
Expected return on plan assets	(3)		(3)
Amortization of prior service cost (credit)	(2)		(1)
Amortization of net transition liability			1
Amortization of actuarial loss (gain)	1		1
Net periodic costs	0		3
Progress Energy [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	15		15
Interest cost on benefit obligation	29		31
Expected return on plan assets	(50)		(46)
Amortization of prior service cost (credit)	(1)		2
Amortization of actuarial loss (gain)	25		22
Other	1		0
Net periodic costs	19		24
Progress Energy [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6		3
Interest cost on benefit obligation	11		10
Amortization of net transition liability			1
Amortization of actuarial loss (gain)	14		6
Net periodic costs	31		20
Duke Energy Progress [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5		6
Interest cost on benefit obligation	13		14
Expected return on plan assets	(23)		(24)
Amortization of prior service cost (credit)	0		2
Amortization of actuarial loss (gain)	11		9
Other	0		0
Net periodic costs	6		7
Duke Energy Progress [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3		1
Interest cost on benefit obligation	6		5
Amortization of actuarial loss (gain)	9		3
Net periodic costs	18		9
Duke Energy Florida [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	8		7
Interest cost on benefit obligation	13		13
Expected return on plan assets	(22)		(20)
Amortization of prior service cost (credit)	0		0
Amortization of actuarial loss (gain)	12		11
Other	0		0
Net periodic costs	11		11
Duke Energy Florida [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2		1
Interest cost on benefit obligation	4		4
Amortization of net transition liability			1
Amortization of actuarial loss (gain)	4		3
Net periodic costs	10		9
Duke Energy Ohio [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2		2
Interest cost on benefit obligation	5		8
Expected return on plan assets	(8)		(11)
Amortization of prior service cost (credit)	0		0
Amortization of actuarial loss (gain)	3		2
Other	0		0
Net periodic costs	2	[3]	1	[3]
Regulatory asset amortization	2		2
Duke Energy Ohio [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligation			1
Amortization of actuarial loss (gain)			(1)
Net periodic costs			0	[4]
Regulatory asset amortization	1		1
Duke Energy Indiana [Member] | Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3		2
Interest cost on benefit obligation	7		8
Expected return on plan assets	(11)		(12)
Amortization of prior service cost (credit)	0		1
Amortization of actuarial loss (gain)	6		3
Other	0		0
Net periodic costs	5		2
Duke Energy Indiana [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligation	1		2
Amortization of actuarial loss (gain)	(1)
Net periodic costs	$ 0		$ 2

[1] Duke Energy amounts exclude $3 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[2] Duke Energy amounts exclude $2 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[3] Duke Energy Ohio amounts exclude $2 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.

[4] Duke Energy Ohio amounts exclude $1 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.