Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Inventory)(Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Public Utilities, Inventory [Line Items]
Materials and supplies	$ 2,102	$ 1,901
Coal held for electric generation	997us-gaap_EnergyRelatedInventoryCoal	1,018us-gaap_EnergyRelatedInventoryCoal
Oil, gas and other fuel held for electric generation	360	331
Public Utilities, Inventory	3,459us-gaap_PublicUtilitiesInventory	3,250us-gaap_PublicUtilitiesInventory
Duke Energy Carolinas [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	719	654
Coal held for electric generation	362	374
Oil, gas and other fuel held for electric generation	43	37
Public Utilities, Inventory	1,124	1,065
Progress Energy [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	981	854
Coal held for electric generation	329	334
Oil, gas and other fuel held for electric generation	280	236
Public Utilities, Inventory	1,590	1,424
Duke Energy Progress [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	676	567
Coal held for electric generation	150	187
Oil, gas and other fuel held for electric generation	140	99
Public Utilities, Inventory	966	853
Duke Energy Florida [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	305	287
Coal held for electric generation	178	147
Oil, gas and other fuel held for electric generation	140	137
Public Utilities, Inventory	623	571
Duke Energy Ohio [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	67	117
Coal held for electric generation	21	65
Oil, gas and other fuel held for electric generation	9	47
Public Utilities, Inventory	97	229
Duke Energy Indiana [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	258	193
Coal held for electric generation	275	238
Oil, gas and other fuel held for electric generation	4	3
Public Utilities, Inventory	$ 537	$ 434

Carrying amount as of the balance sheet date of coal, which is a combustible rock or minerals which are extracted from the ground and used as fuel.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

+ Details

Name:	us-gaap_EnergyRelatedInventoryCoal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of other types of fuel derived from living matter of a previous geologic time, not otherwise itemized.

+ References

+ Details

Name:	us-gaap_EnergyRelatedInventoryOtherFossilFuel
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(4),(5))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryRawMaterialsAndSupplies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The period end amount for a type of inventory held by the utility in a schedule of inventories.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Inventory

-URI http://asc.fasb.org/extlink&oid=6516093

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-05.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_PublicUtilitiesInventory
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_PublicUtilitiesInventoryLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=duk_DukeEnergyCarolinasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=duk_DukeEnergyFloridaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=duk_DukeEnergyIndianaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=duk_DukeEnergyOhioMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=duk_DukeEnergyProgressMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=duk_ProgressEnergyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: