Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating Revenue:
Operating Revenue	$ 60,004		$ 712,189		$ 619,148	$ 1,368,940
Operating Expenses:
Wages and benefits	30,329		180,070		218,583	355,135
Aircraft fuel, including taxes and delivery	7,003		140,600		120,481	266,704
Maintenance, materials and repairs	13,994		58,131		74,403	121,176
Aircraft and passenger servicing	3,036		39,641		41,319	78,541
Depreciation and amortization	39,333		39,527		78,782	77,678
Aircraft rent	23,886		30,843		50,890	61,239
Commissions and other selling	2,927		32,471		29,643	63,307
Other rentals and landing fees	13,677		31,386		43,443	62,432
Purchased services	19,887		32,733		54,128	65,186
Special items	34,014		0		160,918	0
Other	20,882		37,906		63,618	75,985
Total	208,968		623,308		936,208	1,227,383
Operating Income (Loss)	(148,964)		88,881		(317,060)	141,557
Nonoperating Income (Expense):
Interest expense and amortization of debt discounts and issuance costs	(8,221)		(7,300)		(15,016)	(14,830)
Gains (losses) on fuel derivatives	(184)		(3,220)		(6,636)	(2,650)
Interest income	2,766		3,074		5,786	6,057
Capitalized interest	921		1,257		1,752	2,542
Other, net	1,161		(3,083)		3,465	(4,108)
Total	(3,557)		(9,272)		(10,649)	(12,989)
Income (Loss) Before Income Taxes	(152,521)		79,609		(327,709)	128,568
Income tax expense (benefit)	(45,617)		21,776		(76,433)	34,377
Net Income (Loss)	$ (106,904)	$ (144,372)	$ 57,833	$ 36,358	$ (251,276)	$ 94,191
Net Income (Loss) Per Share
Basic (in dollars per share)	$ (2.33)		$ 1.21		$ (5.47)	$ 1.96
Diluted (in dollars per share)	$ (2.33)		$ 1.21		$ (5.47)	$ 1.96
Weighted Average Number of Common Stock Shares Outstanding:
Basic (in shares)	45,971		47,854		45,969	48,122
Diluted (in shares)	45,971		47,889		45,969	48,158
Passenger
Operating Revenue:
Operating Revenue	$ 29,762		$ 653,423		$ 533,231	$ 1,254,727
Other
Operating Revenue:
Operating Revenue	$ 30,242		$ 58,766		$ 85,917	$ 114,213