Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 40	$ 34
Interest cost on projected benefit obligation	82	86
Expected return on plan assets	(129)	(128)
Amortization of actuarial loss (gain)	43	37
Amortization of prior service cost (credit)	(4)	(4)
Other	2	2
Net periodic costs	34	27
Qualified Pension Plans [Member] \| Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	13	10
Interest cost on projected benefit obligation	21	21
Expected return on plan assets	(36)	(33)
Amortization of actuarial loss (gain)	10	9
Amortization of prior service cost (credit)	(2)	(2)
Other	1	1
Net periodic costs	7	6
Qualified Pension Plans [Member] \| Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	11	10
Interest cost on projected benefit obligation	26	28
Expected return on plan assets	(43)	(43)
Amortization of actuarial loss (gain)	17	17
Amortization of prior service cost (credit)	(1)	(1)
Other	1	1
Net periodic costs	11	12
Qualified Pension Plans [Member] \| Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	5
Interest cost on projected benefit obligation	12	13
Expected return on plan assets	(20)	(21)
Amortization of actuarial loss (gain)	8	8
Net periodic costs	6	5
Qualified Pension Plans [Member] \| Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	5	5
Interest cost on projected benefit obligation	14	14
Expected return on plan assets	(22)	(21)
Amortization of actuarial loss (gain)	8	8
Net periodic costs	5	6
Qualified Pension Plans [Member] \| Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1
Interest cost on projected benefit obligation	5	5
Expected return on plan assets	(6)	(7)
Amortization of actuarial loss (gain)	2	1
Net periodic costs	2	0
Qualified Pension Plans [Member] \| Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	2
Interest cost on projected benefit obligation	7	7
Expected return on plan assets	(10)	(9)
Amortization of actuarial loss (gain)	3	3
Net periodic costs	3	3
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2	2
Interest cost on projected benefit obligation	9	12
Expected return on plan assets	(3)	(3)
Amortization of actuarial loss (gain)	6	10
Amortization of prior service cost (credit)	(35)	(31)
Net periodic costs	(21)	(10)
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	3
Expected return on plan assets	(2)	(2)
Amortization of actuarial loss (gain)		1
Amortization of prior service cost (credit)	(4)	(3)
Net periodic costs	(4)	(1)
Other Post-Retirement Benefit Plans [Member] \| Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1
Interest cost on projected benefit obligation	4	6
Amortization of actuarial loss (gain)	7	10
Amortization of prior service cost (credit)	(26)	(24)
Net periodic costs	(15)	(7)
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	3
Amortization of actuarial loss (gain)	5	7
Amortization of prior service cost (credit)	(17)	(18)
Net periodic costs	(10)	(8)
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1
Interest cost on projected benefit obligation	2	3
Amortization of actuarial loss (gain)	3	2
Amortization of prior service cost (credit)	(9)	(5)
Net periodic costs	(4)	1
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic costs	0	0
Other Post-Retirement Benefit Plans [Member] \| Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation		1
Net periodic costs	$ 0	$ 1

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

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Balance Type:	credit
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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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Period Type:	duration

- 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

+ Details

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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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Balance Type:	debit
Period Type:	duration

- 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

+ Details

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- Definition

Amount of other defined benefit plan costs.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

+ Details

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Period Type:	duration

- Details

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