Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 3,455	$ 3,244
Other debt obligations [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 605
Parent Company [Member] \| Unsecured Debt [Member] \| Debt Maturing September 2019, 5.050% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.05%
Current maturities of long-term debt	$ 500
Progress Energy [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 1,322	771
Progress Energy [Member] \| Unsecured Debt [Member] \| Debt Maturing March 2019, 7.050% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	7.05%
Current maturities of long-term debt	$ 450
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 350	250
Piedmont Natural Gas [Member] \| Unsecured Debt [Member] \| Debt Maturing September 2019, 2.848% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	2.848%
Current maturities of long-term debt	$ 350
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 506	1,205
Duke Energy Carolinas [Member] \| First Mortgage Bonds [Member] \| Bonds Maturing November 2018, 7.000% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	7.00%
Current maturities of long-term debt	$ 500
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 603	3
Duke Energy Progress [Member] \| First Mortgage Bonds [Member] \| Bonds Maturing January 2019, 5.300% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.30%
Current maturities of long-term debt	$ 600
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 452	$ 3
Duke Energy Ohio [Member] \| First Mortgage Bonds [Member] \| Bonds Maturing April 2019, 5.450% Coupon [Member] [Member]
Debt Instrument [Line Items]
Interest rate	5.45%
Current maturities of long-term debt	$ 450

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	na
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant