v3.26.1
Debt
 6 Months Ended
Mar. 31, 2026
Debt Disclosure [Abstract]  
Debt Debt
The nature and terms of our debt instruments and credit facilities are described in detail in Note 8 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. Other than as described below, there were no material changes in the terms of our debt instruments during the six months ended March 31, 2026.
Long-term debt at March 31, 2026 and September 30, 2025 consisted of the following:
March 31, 2026September 30, 2025
 (In thousands)
Unsecured 3.00% Senior Notes, due June 2027
$500,000 $500,000 
Unsecured 2.625% Senior Notes, due September 2029
500,000 500,000 
Unsecured 1.50% Senior Notes, due January 2031
600,000 600,000 
Unsecured 5.45% Senior Notes, due October 2032
300,000 300,000 
Unsecured 5.90% Senior Notes, due November 2033
725,000 725,000 
Unsecured 5.95% Senior Notes, due October 2034
200,000 200,000 
Unsecured 5.20% Senior Notes, due August 2035
500,000 500,000 
Unsecured 5.50% Senior Notes, due June 2041
400,000 400,000 
Unsecured 4.15% Senior Notes, due January 2043
500,000 500,000 
Unsecured 4.125% Senior Notes, due October 2044
750,000 750,000 
Unsecured 4.30% Senior Notes, due October 2048
600,000 600,000 
Unsecured 4.125% Senior Notes, due March 2049
450,000 450,000 
Unsecured 3.375% Senior Notes, due September 2049
500,000 500,000 
Unsecured 2.85% Senior Notes, due February 2052
600,000 600,000 
Unsecured 5.75% Senior Notes, due October 2052
500,000 500,000 
Unsecured 6.20% Senior Notes, due November 2053
500,000 500,000 
Unsecured 5.00% Senior Notes, due December 2054
650,000 650,000 
Unsecured 5.45% Senior Notes, due January 2056
600,000 — 
Medium-term note Series A, 1995-1, 6.67%, due December 2025
— 10,000 
Unsecured 6.75% Debentures, due July 2028
150,000 150,000 
Finance lease obligations101,802 47,234 
Total long-term debt9,626,802 8,982,234 
Less:
Original issue (premium) discount on unsecured senior notes and debentures2,602 (1,332)
Debt issuance cost67,576 64,622 
Current maturities of long-term debt2,395 11,775 
Total long-term debt, net$9,554,229 $8,907,169 
On October 1, 2025, we completed a public offering of $600 million of 5.45% senior notes due January 2056, with an effective interest rate of 4.85%, after giving effect to the offering costs and settlement of our interest rate swaps. The net proceeds from the offering, after the underwriting discount and offering expenses, of $590.0 million were used for general corporate purposes.
Short-term debt
We utilize short-term debt to provide cost-effective, short-term financing until it can be replaced with a balance of long-term debt and equity financing that achieves the Company’s desired capital structure. Our short-term borrowing requirements are driven primarily by construction work in progress and the seasonal nature of the natural gas business.
Our short-term borrowing requirements are satisfied through a combination of a $1.5 billion commercial paper program and four committed revolving credit facilities with third-party lenders that provide $3.1 billion of total working capital funding.
The primary source of our funding is our commercial paper program, which is supported by a five-year unsecured $1.5 billion credit facility. On March 27, 2026, we elected to extend the maturity date from March 28, 2030 to March 28, 2031. This facility bears interest at a base rate or at a Term SOFR-based rate for the applicable interest period, plus a margin ranging from zero percent to 0.25 percent for base rate advances or a margin ranging from 0.75 percent to 1.25 percent for Term SOFR-based advances, based on the Company’s credit ratings. Additionally, the facility contains a $250 million accordion feature,
which provides the opportunity to increase the total committed loan to $1.75 billion. At March 31, 2026 and September 30, 2025, there were no amounts outstanding under our commercial paper program.
We also have a $1.5 billion three-year senior unsecured credit facility that is used to provide additional working capital funding. On March 27, 2026, we elected to extend the maturity date from March 28, 2028 to March 28, 2029. This facility bears interest at a base rate or at a Term SOFR-based rate for the applicable interest period, plus a margin ranging from zero percent to 0.25 percent for base rate advances or a margin ranging from 0.75 percent to 1.25 percent for Term SOFR-based advances, based on the Company's credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the total committed loan to $1.75 billion. At March 31, 2026 and September 30, 2025, there were no borrowings outstanding under this facility.
Additionally, we have a $50 million 364-day unsecured facility, which was renewed April 1, 2026 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of March 31, 2026 and September 30, 2025.
Finally, we have a $50 million 364-day unsecured revolving credit facility, which was renewed March 31, 2026 and is used to issue letters of credit and to provide working capital funding. At March 31, 2026, there were no borrowings outstanding under this facility; however, outstanding letters of credit reduced the total amount available to us to $44.4 million.
Debt covenants
The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total-debt-to-total-capitalization of no greater than 70 percent. At March 31, 2026, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 40 percent. In addition, both the interest margin and the fee that we pay on unused amounts under certain of these facilities are subject to adjustment depending upon our credit ratings.
These credit facilities and our public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales, and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as certain of our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or if not paid at maturity. We were in compliance with all of our debt covenants as of March 31, 2026. If we were unable to comply with our debt covenants, we would likely be required to repay our outstanding balances on demand, provide additional collateral or take other corrective actions.