CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
OPERATING REVENUES:
Passenger	$ 812,295	$ 781,475	$ 2,349,047	$ 2,310,678
Ground handling and other	19,641	18,301	58,063	52,512
Total operating revenues	831,936	799,776	2,407,110	2,363,190
OPERATING EXPENSES:
Salaries, wages and benefits	303,997	305,958	899,966	915,743
Aircraft maintenance, materials and repairs	148,787	143,573	433,467	424,722
Depreciation and amortization	74,095	71,743	215,415	209,431
Aircraft rentals	54,976	65,766	168,098	205,458
Aircraft fuel	42,071	33,189	113,564	90,827
Ground handling services	16,693	16,498	52,130	54,225
Other operating expenses	78,948	77,215	229,211	231,004
Total operating expenses	719,567	713,942	2,111,851	2,131,410
OPERATING INCOME	112,369	85,834	295,259	231,780
OTHER INCOME (EXPENSE):
Interest income and other	1,408	591	3,398	1,506
Interest expense	(27,101)	(19,865)	(78,713)	(55,876)
Total other expense, net	(25,693)	(19,274)	(75,315)	(54,370)
INCOME BEFORE INCOME TAXES	86,676	66,560	219,944	177,410
PROVISION FOR INCOME TAXES	32,960	25,238	80,966	68,751
NET INCOME	$ 53,716	$ 41,322	$ 138,978	$ 108,659
BASIC EARNINGS PER SHARE (in dollars per share)	$ 1.04	$ 0.80	$ 2.68	$ 2.11
DILUTED EARNINGS PER SHARE (in dollars per share)	$ 1.01	$ 0.79	$ 2.62	$ 2.08
Weighted average common shares:
Basic (in shares)	51,833	51,627	51,801	51,421
Diluted (in shares)	53,080	52,471	53,087	52,224
COMPREHENSIVE INCOME:
Net income	$ 53,716	$ 41,322	$ 138,978	$ 108,659
Net unrealized appreciation (depreciation) on marketable securities, net of taxes	11	(11)	67	217
TOTAL COMPREHENSIVE INCOME	$ 53,727	$ 41,311	$ 139,045	$ 108,876