CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
OPERATING REVENUES:
Total operating revenues	$ 729,936	$ 723,694
OPERATING EXPENSES:
Salaries, wages and benefits	249,160	257,588
Depreciation and amortization	111,708	89,986
Special items		21,869
Other operating expenses	69,422	63,109
Total operating expenses	663,615	627,275
OPERATING INCOME	66,321	96,419
OTHER INCOME (EXPENSE):
Interest income	2,564	3,807
Interest expense	(30,204)	(32,507)
Other income (expense), net	398	46,725
Total other income (expense), net	(27,242)	18,025
INCOME BEFORE INCOME TAXES	39,079	114,444
PROVISION FOR INCOME TAXES	9,091	26,263
NET INCOME	$ 29,988	$ 88,181
BASIC EARNINGS PER SHARE (in dollars per share)	$ 0.60	$ 1.71
DILUTED EARNINGS PER SHARE (in dollars per share)	$ 0.59	$ 1.69
Weighted average common shares:
Basic (in shares)	50,277	51,440
Diluted (in shares)	50,559	52,098
COMPREHENSIVE INCOME:
Net income	$ 29,988	$ 88,181
Net unrealized appreciation on marketable securities, net of taxes		32
TOTAL COMPREHENSIVE INCOME	29,988	88,213
Flying agreements
OPERATING REVENUES:
Total operating revenues	709,494	700,001
Lease, airport services and other
OPERATING REVENUES:
Total operating revenues	20,442	23,693
Airport customer service and other
OPERATING REVENUES:
Total operating revenues	20,442	23,693
Aircraft maintenance, materials and repairs
OPERATING EXPENSES:
Total operating expenses	160,216	118,262
Airport related expenses
OPERATING EXPENSES:
Total operating expenses	30,640	30,647
Aircraft fuel
OPERATING EXPENSES:
Total operating expenses	25,413	25,656
Aircraft rentals
OPERATING EXPENSES:
Total operating expenses	$ 17,056	$ 20,158