Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt)(Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 2,852,000,000	$ 3,244,000,000
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	602,000,000
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 250,000,000	250,000,000
Piedmont Natural Gas [Member] \| Unsecured Debt [Member] \| Debt Maturing December 2018, Floating Rate [Member]
Debt Instrument [Line Items]
Interest rate	2.796%
Current maturities of long-term debt	$ 250,000,000
Progress Energy [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 1,321,000,000	771,000,000
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	$ 450,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 505,000,000	1,205,000,000
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	$ 500,000,000
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 603,000,000	3,000,000
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	$ 600,000,000
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 452,000,000	$ 3,000,000
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	$ 450,000,000

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

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

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