Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
REVENUES	$ 892,345	$ 1,068,200	$ 768,870
OPERATING EXPENSES
Salaries, wages and benefits	300,514	276,106	224,852
Fuel	39,293	149,579	87,134
Maintenance, materials and repairs	146,692	141,575	119,123
Depreciation and amortization	178,895	154,556	135,496
Travel	34,443	27,390	20,048
Contracted ground and aviation services	16,640	147,092	57,491
Rent	13,899	13,629	11,625
Landing and ramp	5,968	22,271	13,455
Insurance	6,112	4,820	4,456
Transaction fees	5,264	0	0
Other operating expenses	33,607	31,782	24,627
Operating Expenses	781,327	968,800	698,307
OPERATING INCOME	111,018	99,400	70,563
OTHER INCOME (EXPENSE)
Interest income	251	116	131
Non-service component of retiree benefit costs	8,180	(6,105)	(6,815)
Non-service component of retiree benefit (costs) gains	(28,799)	(17,023)	(11,318)
Net gain (loss) on financial instruments	7,296	(79,789)	(18,107)
Other Nonoperating Income (Expense)	(23,540)	(105,936)	(36,109)
EARNINGS (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	87,478	(6,536)	34,454
INCOME TAX BENEFIT (EXPENSE)	(19,595)	28,276	(13,394)
EARNINGS FROM CONTINUING OPERATIONS	67,883	21,740	21,060
EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAXES	1,402	(3,245)	2,428
NET EARNINGS	$ 69,285	$ 18,495	$ 23,488
BASIC EARNINGS (LOSS) PER SHARE
Basic earnings per share from continuing operations (in dollars per share)	$ 1.16	$ 0.37	$ 0.34
Discontinued operations (in dollars per share)	0.02	(0.06)	0.04
TOTAL BASIC EARNINGS PER SHARE (in dollars per share)	1.18	0.31	0.38
DILUTED EARNINGS (LOSS) PER SHARE
Diluted earnings per share from continuing operations (in dollars per share)	0.89	0.36	0.33
Discontinued operations (in dollars per share)	0.02	(0.05)	0.04
TOTAL DILUTED NET EARNINGS PER SHARE (in dollars per share)	$ 0.91	$ 0.31	$ 0.37
WEIGHTED AVERAGE SHARES
Basic (in shares)	58,765	58,907	61,330
Diluted (in shares)	68,356	59,686	62,994