CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
OPERATING ACTIVITIES:
Net earnings from continuing operations	$ 59,748	$ 196,438	$ 228,980
Net earnings from discontinued operations	579	2,143	2,440
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	363,528	355,848	341,849
Pension and post-retirement	18,980	2,675	7,244
Deferred income taxes	16,529	54,862	70,544
Amortization of stock-based compensation	8,516	8,342	7,386
Loss from non-consolidated affiliates	4,740	7,607	2,577
Net loss (gain) on financial instruments	962	(9,022)	(29,979)
Debt issuance costs	936	0	6,505
Changes in assets and liabilities:
Accounts receivable	79,185	(96,223)	(51,888)
Inventory and prepaid supplies	11,997	(18,981)	(3,123)
Accounts payable	58,151	6,047	30,388
Unearned revenue	10,634	(26,430)	(7,011)
Accrued expenses, salaries, wages, benefits and other liabilities	(2,382)	14,755	10,059
Pension and post-retirement balances	16,472	(24,258)	(26,884)
Other	5,506	(1,683)	(5,530)
NET CASH PROVIDED BY OPERATING ACTIVITIES	654,081	472,120	583,557
INVESTING ACTIVITIES:
Expenditures for property and equipment	(793,447)	(599,431)	(504,748)
Proceeds from property and equipment	29,118	15,913	19,427
Acquisitions and investments in businesses	(1,600)	(16,545)	(2,155)
NET CASH (USED IN) INVESTING ACTIVITIES	(765,929)	(600,063)	(487,476)
FINANCING ACTIVITIES:
Principal payments on long term obligations	(225,639)	(365,628)	(1,900,311)
Proceeds from revolving credit facilities	335,000	625,000	1,500,600
Payments for financing costs	(10,779)	(1,803)	(3,099)
Proceeds from convertible note issuance	400,000	0	0
Repurchase of convertible notes	203,247	0	0
Repurchase of senior unsecured notes	0	(115,204)	0
Proceeds from bond issuance	0	0	207,400
Proceeds from issuance of warrants	0	0	131,967
Purchase of common stock	(155,349)	(53,868)	0
Withholding taxes paid for conversion of employee stock awards	(2,986)	(2,916)	(2,861)
Other financing related proceeds	1,269	0	0
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	138,269	85,581	(66,304)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	26,421	(42,362)	29,777
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	27,134	69,496	39,719
CASH AND CASH EQUIVALENTS AT END OF YEAR	53,555	27,134	69,496
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid, net of amount capitalized	51,873	47,194	43,696
Federal and state income taxes paid	6,835	6,205	3,431
SUPPLEMENTAL NON-CASH INFORMATION:
Accrued expenditures for property and equipment	$ 41,703	$ 56,433	$ 43,479