CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
OPERATING ACTIVITIES:
Net earnings from continuing operations	$ 196,438	$ 228,980	$ 25,079
Net earnings from discontinued operations	2,143	2,440	7,036
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	355,848	341,849	310,317
Pension and post-retirement	2,675	7,244	3,888
Deferred income taxes	54,862	70,544	18,492
Amortization of stock-based compensation	8,342	7,386	7,477
Loss from non-consolidated affiliates	7,607	2,577	13,587
Net (gain) loss on financial instruments	(9,022)	(29,979)	100,771
Debt issuance costs	0	6,505	0
Impairment of aircraft and related assets	0	0	39,075
Changes in assets and liabilities:
Accounts receivable	(96,223)	(51,888)	9,359
Inventory and prepaid supplies	(18,981)	(3,123)	(27,825)
Accounts payable	6,047	30,388	5,584
Unearned revenue	(26,430)	(7,011)	36,922
Accrued expenses, salaries, wages, benefits and other liabilities	14,755	10,059	(5,226)
Pension and post-retirement balances	(24,258)	(26,884)	(28,198)
Other	(1,683)	(5,530)	(4,036)
NET CASH PROVIDED BY OPERATING ACTIVITIES	472,120	583,557	512,302
INVESTING ACTIVITIES:
Expenditures for property and equipment	(599,431)	(504,748)	(510,417)
Proceeds from property and equipment	15,913	19,427	24,583
Acquisitions and investments in businesses, net of cash acquired	(16,545)	(2,155)	(13,333)
NET CASH (USED IN) INVESTING ACTIVITIES	(600,063)	(487,476)	(499,167)
FINANCING ACTIVITIES:
Principal payments on long term obligations	(365,628)	(1,900,311)	(689,380)
Proceeds from revolving credit facilities	625,000	1,500,600	180,000
Payments for financing costs	(1,803)	(3,099)	(7,507)
Proceeds from bond issuance	0	207,400	500,000
Repurchase of senior unsecured notes	(115,204)	0	0
Proceeds from issuance of warrants	0	131,967	0
Purchase of common stock	(53,868)	0	0
Withholding taxes paid for conversion of employee stock awards	(2,916)	(2,861)	(2,730)
NET CASH (USED IN) PROVIDED BY FINANCING ACTIVITIES	85,581	(66,304)	(19,617)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(42,362)	29,777	(6,482)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	69,496	39,719	46,201
CASH AND CASH EQUIVALENTS AT END OF YEAR	27,134	69,496	39,719
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid, net of amount capitalized	47,194	43,696	41,343
Federal and state income taxes paid	6,205	3,431	1,139
SUPPLEMENTAL NON-CASH INFORMATION:
Accrued expenditures for property and equipment	$ 56,433	$ 43,479	$ 37,880