Debt

Long-term debt

Long-term debt at September 30, 2018 and 2017 consisted of the following:



	2018			2017
	(In thousands)
Unsecured 8.50% Senior Notes, due March 2019	$	450,000		$	450,000
Unsecured 3.00% Senior Notes, due 2027	500,000			500,000
Unsecured 5.95% Senior Notes, due 2034	200,000			200,000
Unsecured 5.50% Senior Notes, due 2041	400,000			400,000
Unsecured 4.15% Senior Notes, due 2043	500,000			500,000
Unsecured 4.125% Senior Notes, due 2044	750,000			750,000
Medium term Series A notes, 1995-1, 6.67%, due 2025	10,000			10,000
Unsecured 6.75% Debentures, due 2028	150,000			150,000
Floating-rate term loan, due September 2019⁽¹⁾	125,000			125,000
Total long-term debt	3,085,000			3,085,000
Less:
Original issue (premium) / discount on unsecured senior notes and debentures	(4,439		)	(4,384		)
Debt issuance cost	20,774			22,339
Current maturities	575,000			—
	$	2,493,665		$	3,067,045


(1)	Up to $200 million can be drawn under this term loan.

Maturities of long-term debt at September 30, 2018 were as follows (in thousands):



2019	$	575,000
2020	—
2021	—
2022	—
2023	—
Thereafter	2,510,000
	$	3,085,000

On October 4, 2018, we completed a public offering of $600 million of 4.30% senior notes due 2048. We received net proceeds from the offering, after the underwriting discount and estimated offering expenses, of approximately $591 million, that were used to repay working capital borrowings pursuant to our commercial paper program. The effective interest rate of these notes is 4.37% after giving effect to the offering costs.

On June 8, 2017, we completed a public offering of $500 million of 3.00% senior notes due 2027 and $250 million of 4.125% senior notes due 2044. The effective rate of these notes is 3.12% and 4.40%, after giving effect to the offering costs and the settlement of the associated forward starting interest rate swaps. The net proceeds, excluding the loss on the settlement of the interest rate swaps of $37 million, of approximately $753 million were used to repay our $250 million 6.35% senior unsecured notes at maturity on June 15, 2017 and for general corporate purposes, including the repayment of working capital borrowings pursuant to our commercial paper program.

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 with an equity-to-capitalization ratio between 50% and 60%, inclusive of long-term and short-term debt. Our short-term borrowing requirements are affected primarily by the seasonal nature of the natural gas business. Changes in the price of natural gas and the amount of natural gas we need to supply our customers’ needs could significantly affect our borrowing requirements. Our short-term borrowings typically reach their highest levels in the winter months.

Currently, our short-term borrowing requirements are satisfied through a combination of a $1.5 billion commercial paper program and three committed revolving credit facilities with third-party lenders that provide approximately $1.5 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 26, 2018, we executed one of our two one-year extension options which extended the maturity date from September 25, 2021 to September 25, 2022. The facility bears interest at a base rate or at a LIBOR-based rate for the applicable interest period, plus a spread ranging from zero percent to 1.25 percent, 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 September 30, 2018 and 2017, there was $575.8 million and $447.7 million outstanding under our commercial paper program with weighted average interest rates of 2.15% and 1.25%, with weighted average maturities of less than one month.

Additionally, we have a $25 million 364-day unsecured facility, which was renewed on April 1, 2018 and expires March 31, 2019, and a $10 million 364-day unsecured revolving credit facility, which is used primarily to issue letters of credit and which was renewed on September 30, 2018. At September 30, 2018, there were no borrowings outstanding under either of these facilities; however, outstanding letters of credit reduced the total amount available to us under our $10 million unsecured revolving facility to $4.4 million.

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 September 30, 2018, our total-debt-to-total-capitalization ratio, as defined, was 44 percent. In addition, both the interest margin and the fee that we pay on unused amounts under each 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 is not paid at maturity. We were in compliance with all of our debt covenants as of September 30, 2018. 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.