Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Write off of Deferred Debt Issuance Cost	$ 13,587	$ 17,445	$ 10,468
Purchase of common stock	0	0	(3,581)
Withholding taxes paid for conversion of employee stock awards	2,730	2,438	2,325
OPERATING ACTIVITIES:
Net earnings from continuing operations	25,079	59,983	67,883
Net earnings from discontinued operations	7,036	1,219	1,402
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	310,317	285,353	204,559
Pension and post-retirement	3,888	15,700	3,766
Deferred income taxes	18,492	10,478	18,986
Amortization of stock-based compensation	7,477	7,002	5,047
Net (gain) loss on financial instruments	5,300	10,000	8
Changes in assets and liabilities:
Accounts receivable	9,359	(14,551)	25,380
Inventory and prepaid supplies	(27,825)	(6,493)	(3,273)
Accounts payable	5,584	3,340	10,724
Unearned revenue	36,922	1,446	(3,824)
Accrued expenses, salaries, wages, benefits and other liabilities	(5,226)	13,390	3,605
Pension and post-retirement balances	(28,198)	(12,132)	(35,293)
Other	(4,036)	2,456	(4,109)
NET CASH PROVIDED BY OPERATING ACTIVITIES	512,302	396,938	298,025
INVESTING ACTIVITIES:
Expenditures for property and equipment	(510,417)	(453,502)	(292,915)
Proceeds from property and equipment	24,583	10,804	17,570
Investment in nonconsolidated affiliate	(13,333)	(24,360)	(866,558)
NET CASH (USED IN) INVESTING ACTIVITIES	(499,167)	(467,058)	(1,141,903)
FINANCING ACTIVITIES:
Principal payments on long term obligations	(689,380)	(39,500)	(58,640)
Proceeds from borrowings	180,000	100,018	945,000
Payments for financing costs	(7,507)	(1,081)	(9,953)
Proceeds from Issuance of Unsecured Debt	500,000	0	0
NET CASH (USED IN) PROVIDED BY FINANCING ACTIVITIES	(19,617)	56,999	870,501
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(6,482)	(13,121)	26,623
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	46,201	59,322	32,699
CASH AND CASH EQUIVALENTS AT END OF YEAR	39,719	46,201	59,322
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid, net of amount capitalized	41,343	57,546	17,278
Federal and state income taxes paid	1,139	1,294	1,213
SUPPLEMENTAL NON-CASH INFORMATION:
Accrued expenditures for property and equipment	37,880	38,396	11,234
Net (gain) loss on financial instruments	(100,771)	(12,302)	7,296
Accrued consideration for acquisition	0	0	7,845
Asset Impairment Charges	$ 39,075	$ 0	$ 0