Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 135	$ 167	$ 122
Interest cost on projected benefit obligation	344	320	307
Expected return on plan assets	(511)	(549)	(472)
Amortization of actuarial loss (gain)	150	244	144
Amortization of prior service cost (credit)	(15)	(11)	10
Other	8	7	6
Net periodic costs	111	178	117
Qualified Pension Plans [Member] \| Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	41	49	35
Interest cost on projected benefit obligation	85	80	90
Expected return on plan assets	(132)	(148)	(146)
Amortization of actuarial loss (gain)	36	60	45
Amortization of prior service cost (credit)	(8)	(6)	1
Other	2	2	2
Net periodic costs	24	37	27
Qualified Pension Plans [Member] \| Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	40	60	63
Interest cost on projected benefit obligation	112	116	127
Expected return on plan assets	(173)	(199)	(188)
Amortization of actuarial loss (gain)	68	101	93
Amortization of prior service cost (credit)	(3)	(4)	9
Other	3	2	2
Net periodic costs	47	76	106
Qualified Pension Plans [Member] \| Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	21	22	25
Interest cost on projected benefit obligation	54	50	58
Expected return on plan assets	(85)	(94)	(96)
Amortization of actuarial loss (gain)	32	46	37
Amortization of prior service cost (credit)	(2)	(1)	8
Other	1	1	1
Net periodic costs	21	24	33
Qualified Pension Plans [Member] \| Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	20	30	30
Interest cost on projected benefit obligation	57	53	56
Expected return on plan assets	(85)	(87)	(81)
Amortization of actuarial loss (gain)	32	49	48
Amortization of prior service cost (credit)	(1)	(2)	(1)
Other	1	1	1
Net periodic costs	24	44	53
Qualified Pension Plans [Member] \| Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	4	6	6
Interest cost on projected benefit obligation	20	21	31
Expected return on plan assets	(27)	(31)	(45)
Amortization of actuarial loss (gain)	4	13	10
Amortization of prior service cost (credit)			1
Net periodic costs	1	9	3
Qualified Pension Plans [Member] \| Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	9	11	9
Interest cost on projected benefit obligation	29	28	30
Expected return on plan assets	(41)	(46)	(46)
Amortization of actuarial loss (gain)	13	24	15
Amortization of prior service cost (credit)		1	1
Other	1	1
Net periodic costs	11	19	9
Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	3	2
Interest cost on projected benefit obligation	14	13	12
Amortization of actuarial loss (gain)	3	5	4
Amortization of prior service cost (credit)	(1)	(1)	1
Net periodic costs	19	20	19
Non-Qualified Pension Plans [Member] \| Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	1	1	1
Net periodic costs	1	1	1
Non-Qualified Pension Plans [Member] \| Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	2
Interest cost on projected benefit obligation	5	7	8
Amortization of actuarial loss (gain)	2	3	5
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	7	10	14
Non-Qualified Pension Plans [Member] \| Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1
Interest cost on projected benefit obligation	1	1	1
Amortization of actuarial loss (gain)		1	1
Net periodic costs	2	3	3
Non-Qualified Pension Plans [Member] \| Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	1	2
Amortization of actuarial loss (gain)		1
Net periodic costs	2	2	2
Non-Qualified Pension Plans [Member] \| Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic costs	0	0	0
Non-Qualified Pension Plans [Member] \| Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic costs	0	0	0
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	24	16
Interest cost on projected benefit obligation	49	68	56
Expected return on plan assets	(13)	(14)	(17)
Amortization of actuarial loss (gain)	39	52	14
Amortization of prior service cost (credit)	(125)	(41)	(8)
Amortization of net transition liability			10
Other			9
Net periodic costs	(40)	89	80
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2	2	2
Interest cost on projected benefit obligation	12	13	15
Expected return on plan assets	(9)	(11)	(10)
Amortization of actuarial loss (gain)	3	3	3
Amortization of prior service cost (credit)	(11)	(7)	(5)
Amortization of net transition liability			7
Other			1
Net periodic costs	(3)	0	13
Other Post-Retirement Benefit Plans [Member] \| Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	4	18	17
Interest cost on projected benefit obligation	22	41	43
Expected return on plan assets			(2)
Amortization of actuarial loss (gain)	42	57	35
Amortization of prior service cost (credit)	(95)	(30)
Amortization of net transition liability			4
Other			5
Net periodic costs	(27)	86	102
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	9	8
Interest cost on projected benefit obligation	11	22	23
Amortization of actuarial loss (gain)	31	34	20
Amortization of prior service cost (credit)	(73)	(20)
Other			2
Net periodic costs	(30)	45	53
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	7	7
Interest cost on projected benefit obligation	12	16	18
Expected return on plan assets			(2)
Amortization of actuarial loss (gain)	10	16	12
Amortization of prior service cost (credit)	(21)	(6)
Amortization of net transition liability			3
Other			1
Net periodic costs	4	33	39
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1	1
Interest cost on projected benefit obligation	2	2	3
Expected return on plan assets		(1)	(1)
Amortization of actuarial loss (gain)	(2)	(1)	(2)
Amortization of prior service cost (credit)		(1)	(1)
Net periodic costs	0	0	0
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1
Interest cost on projected benefit obligation	5	5	6
Expected return on plan assets	(1)	(1)	(1)
Amortization of actuarial loss (gain)		1
Net periodic costs	$ 5	$ 6	$ 6

The amount of gains or losses recognized in net periodic benefit cost.

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- Definition

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

+ References

+ Details

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- Definition

The amount of the transition obligation or asset recognized in net periodic benefit cost.

+ References

+ Details

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- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512136

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Glossary Expected Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512171

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(3)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References

+ Details

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- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

+ References

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- Definition

Amount of other defined benefit plan costs.

+ References

No definition available.

+ Details

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Service Cost (Component of Net Periodic Pension Cost)

-URI http://asc.fasb.org/extlink&oid=6525008

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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