CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
OPERATING REVENUES:
Total operating revenues	$ 656,990	$ 350,039	$ 1,191,545	$ 1,079,975
OPERATING EXPENSES:
Salaries, wages and benefits	233,423	170,218	453,265	419,379
Depreciation and amortization	109,895	131,638	219,492	243,346
Payroll support grant	(114,144)	(151,938)	(307,317)	(151,938)
Other operating expenses	58,286	38,167	112,774	107,589
Total operating expenses	541,967	354,442	995,680	1,018,057
OPERATING INCOME (LOSS)	115,023	(4,403)	195,865	61,918
OTHER INCOME (EXPENSE):
Interest income	210	1,685	494	4,249
Interest expense	(33,940)	(30,926)	(65,294)	(61,130)
Other income, net	80	402	296	800
Total other expense, net	(33,650)	(28,839)	(64,504)	(56,081)
INCOME (LOSS) BEFORE INCOME TAXES	81,373	(33,242)	131,361	5,837
PROVISION (BENEFIT) FOR INCOME TAXES	19,379	(7,527)	33,467	1,564
NET INCOME (LOSS)	$ 61,994	$ (25,715)	$ 97,894	$ 4,273
BASIC EARNINGS (LOSS) PER SHARE (in dollars per share)	$ 1.23	$ (0.51)	$ 1.95	$ 0.09
DILUTED EARNINGS (LOSS) PER SHARE (in dollars per share)	$ 1.22	$ (0.51)	$ 1.93	$ 0.08
Weighted average common shares:
Basic (in shares)	50,346	50,140	50,316	50,208
Diluted (in shares)	50,725	50,140	50,727	50,357
COMPREHENSIVE INCOME (LOSS):
Net income (loss)	$ 61,994	$ (25,715)	$ 97,894	$ 4,273
Net unrealized appreciation on marketable securities, net of taxes		307		307
TOTAL COMPREHENSIVE INCOME (LOSS)	61,994	(25,408)	97,894	4,580
Flying agreements
OPERATING REVENUES:
Total operating revenues	632,967	336,370	1,144,158	1,045,864
Lease, airport services and other
OPERATING REVENUES:
Total operating revenues	24,023	13,669	47,387	34,111
Aircraft maintenance, materials and repairs
OPERATING EXPENSES:
Total operating expenses	190,879	121,289	394,706	281,505
Airport-related expenses
OPERATING EXPENSES:
Total operating expenses	22,038	21,550	46,486	52,190
Aircraft fuel
OPERATING EXPENSES:
Total operating expenses	25,867	6,821	45,061	32,234
Aircraft rentals
OPERATING EXPENSES:
Total operating expenses	$ 15,723	$ 16,697	$ 31,213	$ 33,752