| | | | | | | | | | | | | | | | | | | | | | | |
| For the three months ended September 30, | | For the nine months ended September 30, |
| | 2024 | | 2023 | | 2024 | | 2023 |
| Revenues: | | | | | | | |
| Sales | $ | 319,944 | | | $ | 416,888 | | | $ | 1,208,366 | | | $ | 1,288,412 | |
| Other revenues | 7,776 | | | 6,599 | | | 19,389 | | | 24,409 | |
| Total revenues | 327,720 | | | 423,487 | | | 1,227,755 | | | 1,312,821 | |
| Costs and expenses: | | | | | | | |
| Cost of sales (exclusive of items shown separately below) | 231,598 | | | 260,376 | | | 778,489 | | | 723,458 | |
| Cost of other revenues (exclusive of items shown separately below) | 8,854 | | | 9,855 | | | 29,491 | | | 32,803 | |
| Depreciation and depletion | 36,642 | | | 34,020 | | | 114,815 | | | 101,783 | |
| Selling, general and administrative | 11,403 | | | 11,138 | | | 45,452 | | | 38,826 | |
| Business interruption | 107 | | | 347 | | | 409 | | | 8,101 | |
| | | | | | | |
| Total costs and expenses | 288,604 | | | 315,736 | | | 968,656 | | | 904,971 | |
| Operating income | 39,116 | | | 107,751 | | | 259,099 | | | 407,850 | |
| Interest expense | (1,422) | | | (3,418) | | | (3,458) | | | (16,313) | |
| Interest income | 8,679 | | | 10,691 | | | 26,074 | | | 31,235 | |
| Loss on early extinguishment of debt | — | | | (11,699) | | | — | | | (11,699) | |
| Other expense | — | | | (1,102) | | | — | | | (881) | |
| Income before income tax expense | 46,373 | | | 102,223 | | | 281,715 | | | 410,192 | |
| Income tax expense | 4,607 | | | 16,841 | | | 32,248 | | | 60,439 | |
| Net income | $ | 41,766 | | | $ | 85,382 | | | $ | 249,467 | | | $ | 349,753 | |
| Basic and diluted net income per share: | | | | | | | |
| Net income per share—basic | $ | 0.80 | | | $ | 1.64 | | | $ | 4.78 | | | $ | 6.73 | |
| Net income per share—diluted | $ | 0.80 | | | $ | 1.64 | | | $ | 4.78 | | | $ | 6.72 | |
| Weighted average number of shares outstanding—basic | 52,330 | | | 52,019 | | | 52,167 | | | 51,958 | |
| Weighted average number of shares outstanding—diluted | 52,394 | | | 52,111 | | | 52,221 | | | 52,028 | |
| Dividends per share: | $ | 0.08 | | | $ | 0.07 | | | $ | 0.74 | | | $ | 1.09 | |