CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 72,953	$ 111,910	$ (8,515)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	394,552	440,198	474,959
Stock based compensation expense	9,159	8,685	6,802
Write-off of maintenance assets			3,255
Increase (decrease) in credit loss reserves	(4,591)	(4,249)	17,087
Loss (gain) on disposal of fixed assets	(7,948)	(4,586)	445
Gain on investments in other companies	(11,380)
Net increase in deferred income taxes	23,825	37,305	6,100
Impairment on assets held for sale	51,384
Special items		84,592
Changes in operating assets and liabilities:
Decrease (increase) in receivables	(32,959)	(30,093)	26,831
Decrease (increase) in income tax receivable	7,815	(5,570)	7,225
Decrease (increase) in inventories	(16,628)	(12,897)	19,307
Decrease (increase) in other current assets	(2,871)	(1,936)	8,233
Decrease in operating lease right-of-use assets	86,588	43,846	53,647
Decrease in operating lease liabilities	(76,812)	(51,326)	(65,557)
Increase (decrease) in deferred revenue	40,812	(6,832)	110,728
Increase in unbilled revenue	(11,491)	(8,404)
Increase (decrease) in accounts payable and other current liabilities	(42,032)	231,177	(26,984)
NET CASH PROVIDED BY OPERATING ACTIVITIES	480,376	831,820	633,563
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(1,834,403)	(1,517,861)	(1,347,775)
Sales of marketable securities	1,488,359	1,526,057	1,170,556
Acquisition of property and equipment:
Aircraft and rotable spare parts	(632,460)	(537,574)	(425,618)
Buildings and ground equipment	(13,031)	(18,127)	(12,678)
Proceeds from the sale of property and equipment	16,983	7,117	3,239
Deposits on aircraft	(37,100)	(125,701)	(9,625)
Aircraft deposits applied towards acquired aircraft	138,383	32,962	27,858
Increase in other assets	(31,625)	(65,395)	(89,428)
NET CASH USED IN INVESTING ACTIVITIES	(904,894)	(698,522)	(683,471)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	684,502	450,032	406,364
Principal payments on long-term debt	(415,050)	(540,537)	(187,404)
Payment of debt issuance cost	(2,178)	(1,665)	(4,130)
Net proceeds from issuance of common stock	2,957	3,146	2,819
Employee income tax paid on vested equity awards	(1,150)	(1,576)	(6,165)
Purchase of treasury stock			(20,000)
Payment of cash dividends			(13,059)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	269,081	(90,600)	178,425
Increase (decrease) in cash and cash equivalents	(155,437)	42,698	128,517
Cash and cash equivalents at beginning of period	258,421	215,723	87,206
CASH AND CASH EQUIVALENTS AT END OF PERIOD	102,984	258,421	215,723
Non-cash investing and financing activities:
Acquisition of property and equipment	16,826	11,336	22,187
Warrants issued to U.S. Treasury		5,804	8,248
Cash paid during the period for:
Interest, net of capitalized amounts	125,321	124,918	125,440
Income taxes	$ 1,166	$ 6,589	$ 1,780