CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement [Abstract]
REVENUES	$ 529,339	$ 509,668	$ 1,030,434	$ 995,528
OPERATING EXPENSES
Salaries, wages and benefits	170,458	162,797	347,173	324,559
Depreciation and amortization	82,691	81,372	167,419	163,443
Maintenance, materials and repairs	50,436	39,407	94,269	75,116
Fuel	67,271	73,102	134,026	133,460
Contracted ground and aviation services	19,682	20,153	37,470	38,484
Travel	31,222	28,480	60,775	52,679
Landing and ramp	4,744	4,085	8,868	8,663
Rent	8,274	7,068	16,386	13,731
Insurance	2,684	2,326	5,232	4,878
Other operating expenses	22,136	20,361	41,652	40,204
Operating expenses	459,598	439,151	913,270	855,217
OPERATING INCOME	69,741	70,517	117,164	140,311
OTHER INCOME (EXPENSE)
Interest income	180	15	395	24
Non-service component of retiree benefit (loss) gains	(3,218)	5,388	(6,436)	10,776
Net gain on financial instruments	1,818	6,011	78	8,707
Loss from non-consolidated affiliate	(2,107)	(3,220)	(2,513)	(4,623)
Interest expense	(16,672)	(9,461)	(32,377)	(20,860)
Other Nonoperating Income (Expense)	(19,999)	(1,267)	(40,853)	(5,976)
EARNINGS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	49,742	69,250	76,311	134,335
INCOME TAX EXPENSE	(11,720)	(15,040)	(18,148)	(30,329)
EARNINGS FROM CONTINUING OPERATIONS	38,022	54,210	58,163	104,006
EARNINGS FROM DISCONTINUED OPERATIONS, NET OF TAXES	0	882	0	882
NET EARNINGS	$ 38,022	$ 55,092	$ 58,163	$ 104,888
BASIC EARNINGS PER SHARE
Basic earnings per share from continuing operations (in dollars per share)	$ 0.54	$ 0.73	$ 0.82	$ 1.41
Discontinued operations (in dollars per share)	0	0.01	0	0.01
TOTAL BASIC EARNINGS PER SHARE (in dollars per share)	0.54	0.74	0.82	1.42
DILUTED EARNINGS PER SHARE
Diluted earnings per share from continuing operations (in dollars per share)	0.49	0.61	0.73	1.18
Discontinued operations (in dollars per share)	0	0.01	0	0.01
TOTAL DILUTED NET EARNINGS PER SHARE (in dollars per share)	$ 0.49	$ 0.62	$ 0.73	$ 1.19
WEIGHTED AVERAGE SHARES
Basic (in shares)	70,722	73,980	71,259	73,934
Diluted (in shares)	79,515	89,449	81,276	89,098