| **Debt and Credit Facilities** | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      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| **Debt Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        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| Debt and Credit Facilities     | Debt and Credit FacilitiesSummary of Long-Term DebtOur long-term debt consists of privately placed senior notes issued under note purchase agreements, as well as publicly issued medium-term and senior notes issued under an indenture. All of our long-term debt is unsecured and is issued at fixed rates. None of our debt is actively traded. The tables below reflect the detail of this presentation for our long-term debt as of October 31, 2016 and 2015.  Long-Term Debt as of October 31, 2016(in millions) Principal Unamortized Debt Issuance Expenses and Discounts TotalSenior Notes:      8.51%, due September 30, 2017 $35.0 $— $35.04.24%, due June 6, 2021 160.0 (0.6) 159.43.47%, due July 16, 2027 100.0 (0.6) 99.43.57%, due July 16, 2027 200.0 (1.2) 198.84.10%, due September 18, 2034 250.0 (2.5) 247.54.65%, due August 1, 2043 300.0 (2.9) 297.13.60%, due September 1, 2025 150.0 (1.4) 148.63.64%, due November 1, 2046 300.0 (3.4) 296.6Medium-Term Notes:     6.87%, due October 6, 2023 45.0 (0.1) 44.98.45%, due September 19, 2024 40.0 (0.1) 39.97.40%, due October 3, 2025 55.0 (0.2) 54.87.50%, due October 9, 2026 40.0 (0.1) 39.97.95%, due September 14, 2029 60.0 (0.2) 59.86.00%, due December 19, 2033 100.0 (0.7) 99.3Total 1,835.0 (14.0) 1,821.0Less current maturities 35.0 — 35.0Total $1,800.0 $(14.0) $1,786.0  Long-Term Debt as of October 31, 2015(in millions) Principal Unamortized Debt Issuance Expenses and Discounts TotalSenior Notes:      2.92%, due June 6, 2016 $40.0 $(0.1) $39.98.51%, due September 30, 2017 35.0 — 35.04.24%, due June 6, 2021 160.0 (0.8) 159.23.47%, due July 16, 2027 100.0 (0.6) 99.43.57%, due July 16, 2027 200.0 (1.3) 198.74.10%, due September 18, 2034 250.0 (2.6) 247.44.65%, due August 1, 2043 300.0 (3.0) 297.03.60%, due September 1, 2025 150.0 (1.4) 148.6Medium-Term Notes:      6.87%, due October 6, 2023 45.0 (0.1) 44.98.45%, due September 19, 2024 40.0 (0.1) 39.97.40%, due October 3, 2025 55.0 (0.2) 54.87.50%, due October 9, 2026 40.0 (0.1) 39.97.95%, due September 14, 2029 60.0 (0.3) 59.76.00%, due December 19, 2033 100.0 (0.7) 99.3Total 1,575.0 (11.3) 1,563.7Less current maturities 40.0 — 40.0Total $1,535.0 $(11.3) $1,523.7Current maturities for the next five years ending October 31 and thereafter are as follows.(in millions) 2017$35.02018—2019—2020—2021160.0Thereafter1,640.0Total$1,835.0In June 2014, we filed with the SEC a combined debt and equity shelf registration statement that became effective on June 6, 2014. The NCUC approved debt and equity issuances under this shelf registration statement up to $1.0 billion during its three-year life. As a result of the Acquisition, Piedmont's shelf registration statement is no longer valid for future issuances.On September 14, 2015, we issued $150.0 million of ten-year, unsecured senior notes with an interest rate of 3.60% and at a discount of .065% or $0.1 million under the registration statement in effect noted above. We have the option to redeem all or part of the notes before the stated maturity prior to June 1, 2025, at a redemption price equal to the greater of a) 100% of the principal amount plus any accrued and unpaid interest to the date of redemption, or b) the sum of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed, discounted to the date of redemption on a semi-annual basis at the Treasury Rate as defined in the indenture, plus 25 basis points and any accrued and unpaid interest to the date of redemption. We have the option to redeem all or part of the notes before the stated maturity on or after June 1, 2025, at 100% of the principal amount plus any accrued and unpaid interest to the date of redemption. We used the net proceeds of $148.9 million from this issuance to finance capital expenditures, to repay outstanding short-term, unsecured notes under our CP program and for general corporate purposes.On June 6, 2016, we repaid $40.0 million of our 2.92% senior notes at maturity.On July 28, 2016, we issued $300.0 million of unsecured senior notes maturing November 1, 2046 with an interest rate of 3.64% and at a discount of .122% or $0.4 million under the registration statement in effect noted above. We have the option to redeem all or part of the notes before May 1, 2046, at a redemption price equal to the greater of a) 100% of the principal amount of the notes to be redeemed, and b) the sum of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed, discounted to the date of redemption on a semi-annual basis at the Treasury Rate as defined in the indenture, as supplemented, plus 25 basis points and any accrued and unpaid interest to the date of redemption. We have the option to redeem all or part of the notes on or after May 1, 2046, at 100% of the principal amount plus any accrued and unpaid interest to the date of redemption. We used the net proceeds of $297.0 million from this issuance to finance capital expenditures, to repay outstanding short-term, unsecured notes under our CP program and for general corporate purposes.The amount of cash dividends that may be paid on common stock is restricted by provisions contained in certain note agreements under which long-term debt was issued, with those for the senior notes being the most restrictive. We cannot pay or declare any dividends or make any other distribution on any class of stock or make any investments in subsidiaries or permit any subsidiary to do any of the above (all of the foregoing being "restricted payments"), except out of net earnings available for restricted payments. As of October 31, 2016, our net earnings available for restricted payments were $1.3 billion. We are subject to default provisions related to our long-term debt and short-term borrowings. Failure to satisfy any of the default provisions may result in total outstanding issues of debt becoming due. There are cross default provisions in all of our debt agreements. As of October 31, 2016, we are in compliance with all default provisions.The default provisions of some or all of our senior debt include:•Failure to make principal or interest payments,•Bankruptcy, liquidation or insolvency,•Final judgment against us in excess of $1.0 million that after 60 days is not discharged, satisfied or stayed pending appeal,•Specified events under the Employee Retirement Income Security Act of 1974,•Change in control, and•Failure to observe or perform covenants, including:•Interest coverage of at least 1.75 times. Interest coverage was 4.65 times as of October 31, 2016;•Funded debt cannot exceed 70% of total capitalization. Funded debt was 55% of total capitalization as of October 31, 2016;•Funded debt of all subsidiaries in the aggregate cannot exceed 15% of total capitalization. There is no funded debt of our subsidiaries as of October 31, 2016;•Restrictions on permitted liens;•Restrictions on paying dividends on or repurchasing our stock or making investments in subsidiaries; and•Restrictions on burdensome agreements.The Acquisition constituted a change in control under the note agreements under which our 4.24% Senior Notes due 2021, 3.47% Senior Notes due 2027 and 3.57% Senior Notes due 2027 were issued. While the Acquisition did not constitute an event of default, upon the closing of the Acquisition, we were required to offer to prepay 100% of the principal amounts plus accrued interest to these noteholders. None of the noteholders exercised the prepayment option.Available Credit FacilitiesAt October 31, 2016, we have an $850.0 million five-year revolving syndicated credit facility that expires on December 14, 2020 that has an option to request an expansion up to an additional $200.0 million. We pay an annual fee of $35,000 plus 8.5 basis points for any unused amount. The facility provides a line of credit for letters of credit of $10.0 million, of which $1.7 million and $1.6 million were issued and outstanding as of October 31, 2016 and 2015, respectively. These letters of credit are used to guarantee claims from self-insurance under our general and automobile liability policies. The credit facility bears interest based on the 30-day London Interbank Offered Rate (LIBOR) plus from 75 to 112.5 basis points, based on our credit ratings. Amounts borrowed are continuously renewable until the expiration of the facility in 2020 provided that we are in compliance with all terms of the agreement. The facility expressly permitted the Acquisition by Duke Energy. We have an $850.0 million unsecured CP program that is backstopped by the revolving syndicated credit facility. The amounts outstanding under the revolving syndicated credit facility and the CP program, either individually or in the aggregate, cannot exceed $850.0 million. The notes issued under the CP program may have maturities not to exceed 397 days from the date of issuance and bear interest based on, among other things, the size and maturity date of the note, the frequency of the issuance and our credit ratings, plus a spread of 5 basis points. Any borrowings under the CP program rank equally with our other unsecured debt. The notes under the CP program are not registered and are offered and issued pursuant to an exemption from registration. Due to the seasonal nature of our business, amounts borrowed can vary significantly during the year.As of October 31, 2016, we had $145.0 million of notes outstanding under the CP program, as included in "Notes payable and commercial paper" within "Current Liabilities" on the Consolidated Balance Sheets, with original maturities ranging from 1 to 6 days from their dates of issuance at a weighted average interest rate of .64%. As of October 31, 2015, our outstanding notes under the CP program, included on the Consolidated Balance Sheets as stated above, were $340.0 million at a weighted average interest rate of .22%.Other than outstanding CP balances, we did not have any borrowings under the revolving syndicated credit facility for the twelve months ended October 31, 2016. A summary of the short-term debt activity under our CP program for the twelve months ended October 31, 2016 is as follows.(in millions) Minimum amount outstanding$110.0Maximum amount outstanding$530.0Minimum interest rate.20%Maximum interest rate.75%Weighted average interest rate.55%Our five-year revolving syndicated credit facility’s financial covenants require us to maintain a ratio of total debt to total capitalization of no greater than 70%, and our actual ratio was 55% at October 31, 2016. |

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| - References
No definition available.
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| - Definition
The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.
+ References
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