v3.26.1
Long-Term Debt
6 Months Ended
Jun. 30, 2026
Debt Disclosure [Abstract]  
Long-Term Debt Long-Term Debt
Our outstanding long-term debt is shown below: 
June 30,December 31,
(in millions)20262025
Uncollateralized Senior Notes:
5.68% notes, due June 2026
$ $2.9 
6.39% notes, due December 2026
100.0 100.0 
6.44% notes, due December 2027
100.0 100.0 
6.43% notes, due May 2028
1.4 2.1 
4.88% notes, due August 2028
60.0 60.0 
3.73% notes, due December 2028
6.0 6.0 
6.45% notes, due December 2028
100.0 100.0 
3.88% notes, due May 2029
15.0 20.0 
5.20% notes, due November 2029
100.0 100.0 
5.02% notes, due September 2030
50.0 50.0 
6.62% notes, due December 2030
100.0 100.0 
5.16% notes, due August 2031
90.0 90.0 
3.25% notes, due April 2032
42.0 45.5 
6.71% notes, due December 2033
100.0 100.0 
2.98% notes, due December 2034
63.0 63.0 
3.00% notes, due July 2035
50.0 50.0 
2.96% notes, due August 2035
40.0 40.0 
2.49% notes, due January 2037
50.0 50.0 
5.43% notes, due March 2038
80.0 80.0 
3.48% notes, due May 2038
50.0 50.0 
3.58% notes, due November 2038
50.0 50.0 
6.73% notes, due December 2038
50.0 50.0 
3.98% notes, due August 2039
100.0 100.0 
2.95% notes, due March 2042
50.0 50.0 
Equipment security note
2.46% note, due September 2031
5.3 5.8 
Less: debt issuance costs(3.1)(3.6)
Total long-term debt1,449.6 1,461.7 
Less: current maturities(131.7)(134.6)
Total long-term debt, net of current maturities$1,317.9 $1,327.1 
    

Terms of the Senior Notes

All of our outstanding Senior Notes set forth certain business covenants to which we are subject when any note is outstanding, including covenants that limit or restrict our ability, and the ability of our subsidiaries, to incur indebtedness, or place or permit liens and encumbrances on any of our property or the property of our subsidiaries.

Senior Notes
In August 2025, we entered into a Note Purchase Agreement for the issuance of Senior Notes in the aggregate principal amount of $200.0 million with an initial funding of $150.0 million in August 2025 and an additional $50.0 million in September 2025. These Senior Notes have an average interest rate of 5.04 percent consisting of $60.0 million of 4.88 percent notes due in August 2028, $50.0 million of 5.02 percent notes due in September 2030, and $90.0 million of 5.16 percent notes due in August 2031. The proceeds received were used to reduce short-term borrowings under our Revolver and to fund capital expenditures. The outstanding principal balance of the Senior Notes will be due on their respective maturity dates with interest payments payable semiannually beginning in 2026
until the principal has been paid in full. These Senior Notes have similar covenants and default provisions as our other Senior Notes.

Shelf Agreements
We have entered into Shelf Agreements with Prudential and MetLife, however neither of such lenders have any obligation to purchase debt thereunder. We amended these agreements with Prudential and MetLife in February 2026 and June 2025, respectively, to expand the total borrowing capacity and extend the term of the agreements. At June 30, 2026, a total of $347.5 million of borrowing capacity was available under these agreements with terms that extend through February 2029 and June 2030, respectively.