CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
OPERATING ACTIVITIES
Net income	$ 59,886	$ 136,537
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	62,337	50,328
Stock-based compensation expense	4,608	4,118
Gain on disposition of assets, net	(4,552)	(5,951)
Gain due to benefit plan financing arrangement	(1,151)
Deferred income tax provision	6,668	4,401
Pension settlement charges		18,286
Other non-cash adjustments	193	242
Decrease (increase) in assets:
Accounts receivable	21,716	23,017
Income taxes receivable	44,016	(10,745)
Inventories	(2,648)	(7,001)
Prepaid expenses	4,750	3,327
Other current assets	75	(297)
Other non-current assets	(792)	(833)
Increase (decrease) in liabilities:
Accounts payable	11,760	(30,646)
Income taxes payable	28	(95)
Unearned revenue	(15,743)
Accrued payroll and related expenses	(4,429)	(7,075)
Accrued insurance expenses	414	1,933
Accrued state, local and other taxes	1,147	2,121
Other accrued expenses	(4,562)	(2,938)
Pension and retirement plan liabilities	853	(5,068)
Long-term accrued insurance expenses	1,114	2,491
Other long-term liabilities	(1,201)	1,406
Net cash provided by operating activities	184,487	177,558
INVESTING ACTIVITIES
Capital expenditures	(127,799)	(104,488)
Proceeds from sale of assets	8,883	8,688
Purchase of business		(78,982)
Proceeds from benefit plan financing arrangement	2,380
Re-investment in benefit plan financing arrangement	(2,380)
Net cash used for investing activities	(118,916)	(174,782)
FINANCING ACTIVITIES
Payment of dividends	(17,203)	(17,314)
Cash paid for common stock purchased and retired	(9,858)	(11,351)
Cash paid for finance lease and finance obligations	(304)
Net cash used for financing activities	(27,365)	(28,665)
Net increase (decrease) in cash and cash equivalents	38,206	(25,889)
Cash and cash equivalents at beginning of period	223,310	126,424
Cash and cash equivalents at end of period	261,516	100,535
Supplemental cash flows disclosure:
Income tax (refund) payments, net	(33,403)	48,553
Interest paid	84	83
Supplemental disclosure of noncash investing activities:
Capital expenditures included in accounts payable	$ 12,494	$ 12,769