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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 |

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + 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 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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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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