| | | | | | | | | | | | | | |
| | March 31, | | December 31, |
| (in millions) | | 2026 | | 2025 |
| Uncollateralized Senior Notes: | | | | |
| 5.68% notes, due June 2026 | | $ | 2.9 | | | $ | 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 | | 2.1 | | | 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 | | 20.0 | | | 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 | | 43.8 | | | 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 | | 5.6 | | | 5.8 | |
| Less: debt issuance costs | | (3.5) | | | (3.6) | |
| Total long-term debt | | 1,459.9 | | | 1,461.7 | |
| Less: current maturities | | (134.6) | | | (134.6) | |
| Total long-term debt, net of current maturities | | $ | 1,325.3 | | | $ | 1,327.1 | |