Condensed Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating revenues:
Revenues	$ 1,012,956	$ 851,771	$ 1,868,752	$ 1,555,909
Operating expenses:
Aircraft fuel	265,006	246,180	494,642	450,826
Salaries, wages and benefits	216,375	187,756	420,276	342,852
Landing fees and other rents	64,711	58,602	124,360	108,232
Aircraft rent	46,522	41,745	92,304	91,936
Depreciation and amortization	54,913	45,618	105,639	84,991
Distribution	40,602	34,997	76,321	65,628
Maintenance, materials and repairs	34,688	31,653	66,292	61,363
Special charges	0	174	0	89,342
Loss on disposal of assets	1,550	4,644	3,463	5,492
Other operating	124,651	91,881	233,713	185,523
Total operating expenses	849,018	743,250	1,617,010	1,486,185
Operating income (loss)	163,938	108,521	251,742	69,724
Other (income) expense:
Interest expense	25,266	20,498	50,237	38,347
Capitalized interest	(2,975)	(2,296)	(5,532)	(4,548)
Interest income	(7,066)	(4,430)	(13,990)	(8,496)
Other expense	144	188	377	321
Special charges, non-operating	0	79,412	0	88,613
Total other (income) expense	15,369	93,372	31,092	114,237
Income (loss) before income taxes	148,569	15,149	220,650	(44,513)
Provision (benefit) for income taxes	34,068	3,895	50,073	(10,845)
Net income (loss)	$ 114,501	$ 11,254	$ 170,577	$ (33,668)
Basic earnings (loss) per share	$ 1.67	$ 0.16	$ 2.49	$ (0.49)
Diluted earnings (loss) per share	$ 1.67	$ 0.16	$ 2.49	$ (0.49)
Passenger [Member]
Operating revenues:
Revenues	$ 994,430	$ 836,350	$ 1,832,495	$ 1,525,491
Other [Member]
Operating revenues:
Revenues	$ 18,526	$ 15,421	$ 36,257	$ 30,418