CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Cash flows from operating activities
Net (loss) income	$ 1,366	$ 15,178
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	711	2,321
Loss (gain) on extinguishment of debt	59	(3,013)
Depreciation expense on the related plant, property and equipment	40,765	35,861
Amortization of short term investments	409	5,630
Stock-based compensation	3,821	3,492
Write-downs of property, plant and equipment	2,599	2,943
Other	1,169	1,725
Cash provided (used) by changes in operating assets and liabilities:
Accounts receivable	(12,564)	(1,531)
Inventories	190	6,098
Prepaid insurance	8,420	8,693
Supplies, prepaid items and other	(2,937)	(1,481)
Accounts payable	(16,194)	(5,587)
Accrued interest	(2,745)	(3,749)
Other assets and other liabilities	(68)	(1,091)
Net cash provided by operating activities	25,001	65,489
Cash flows from investing activities
Expenditures for property, plant and equipment	(39,347)	(33,047)
Proceeds from short-term investments	154,565	236,493
Purchases of short-term investments	(110,281)	(34,689)
Other investing activities	(111)	29
Net cash provided by investing activities	4,826	168,786
Cash flows from financing activities
Repurchases of 6.25% Senior Secured Notes	(32,076)	(92,216)
Payments on other long-term debt	(3,323)	(2,925)
Payments on short-term financing	(8,019)	(8,847)
Acquisition of treasury stock, net	157	(12,032)
Taxes paid on equity awards	(1,182)	(2,176)
Payments of debt-related costs	0	(777)
Net cash used by financing activities	(44,443)	(118,973)
Net (decrease) increase in cash and cash equivalents	(14,616)	115,302
Cash and cash equivalents at beginning of period	20,230	101,032
Cash and cash equivalents at end of period	$ 5,614	$ 216,334