Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
REVENUES	$ 1,068,200	$ 768,870	$ 619,264
OPERATING EXPENSES
Salaries, wages and benefits	282,211	231,667	181,785
Fuel	149,579	87,134	52,615
Maintenance, materials and repairs	141,575	119,123	103,961
Depreciation and amortization	154,556	135,496	125,443
Travel	27,390	20,048	18,007
Contracted ground and aviation services	147,092	57,491	18,983
Rent	13,629	11,625	11,677
Landing and ramp	22,271	13,455	9,727
Insurance	4,820	4,456	3,645
Other operating expenses	31,782	24,627	20,631
Operating Expenses	974,905	705,122	546,474
OPERATING INCOME	93,295	63,748	72,790
OTHER INCOME (EXPENSE)
Interest income	116	131	85
Interest expense	(17,023)	(11,318)	(11,232)
Net gain (loss) on financial instruments	(79,789)	(18,107)	920
Other Nonoperating Income (Expense)	(99,831)	(29,294)	(10,227)
EARNINGS (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(6,536)	34,454	62,563
INCOME TAX BENEFIT (EXPENSE)	28,276	(13,394)	(23,408)
EARNINGS FROM CONTINUING OPERATIONS	21,740	21,060	39,155
EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAXES	(3,245)	2,428	2,067
NET EARNINGS	$ 18,495	$ 23,488	$ 41,222
BASIC EARNINGS (LOSS) PER SHARE
Basic earnings per share from continuing operations (in dollars per share)	$ 0.37	$ 0.34	$ 0.61
Discontinued operations (in dollars per share)	(0.06)	0.04	0.03
TOTAL BASIC EARNINGS PER SHARE (in dollars per share)	0.31	0.38	0.64
DILUTED EARNINGS (LOSS) PER SHARE
Diluted earnings per share from continuing operations (in dollars per share)	0.36	0.33	0.60
Discontinued operations (in dollars per share)	(0.05)	0.04	0.03
TOTAL DILUTED NET EARNINGS PER SHARE (in dollars per share)	$ 0.31	$ 0.37	$ 0.63
WEIGHTED AVERAGE SHARES
Basic (in shares)	58,907	61,330	64,242
Diluted (in shares)	59,686	62,994	65,127