Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REVENUES	$ 1,570,575	$ 1,452,183	$ 892,345
OPERATING EXPENSES
Salaries, wages and benefits	518,961	433,518	300,514
Fuel	148,383	155,033	39,293
Maintenance, materials and repairs	179,315	170,151	146,692
Depreciation and amortization	278,067	257,532	178,895
Travel	77,382	90,993	34,443
Contracted ground and aviation services	63,564	64,076	16,640
Rent	19,299	16,006	13,899
Landing and ramp	12,468	11,184	5,968
Insurance	9,903	7,342	6,112
Transaction fees	0	373	5,264
Other operating expenses	64,999	68,978	33,607
government grants continuing operations	(47,231)	0	0
Operating Expenses	1,364,185	1,275,186	781,327
OPERATING INCOME	206,390	176,997	111,018
OTHER INCOME (EXPENSE)
Interest income	222	370	251
Non-service component of retiree benefit costs	12,032	(9,404)	8,180
Non-service component of retiree benefit (costs) gains	(62,893)	(66,644)	(28,799)
Net gain (loss) on financial instruments	(100,771)	(12,302)	7,296
Other Nonoperating Income (Expense)	(164,997)	(105,425)	(23,540)
EARNINGS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	41,393	71,572	87,478
INCOME TAX EXPENSE	(16,314)	(11,589)	(19,595)
EARNINGS FROM CONTINUING OPERATIONS	25,079	59,983	67,883
EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAXES	7,036	1,219	1,402
NET EARNINGS	$ 32,115	$ 61,202	$ 69,285
BASIC EARNINGS PER SHARE
Basic earnings per share from continuing operations (in dollars per share)	$ 0.42	$ 1.02	$ 1.16
Discontinued operations (in dollars per share)	0.12	0.02	0.02
TOTAL BASIC EARNINGS PER SHARE (in dollars per share)	0.54	1.04	1.18
DILUTED EARNINGS PER SHARE
Diluted earnings per share from continuing operations (in dollars per share)	0.42	0.78	0.89
Discontinued operations (in dollars per share)	0.12	0.01	0.02
TOTAL DILUTED NET EARNINGS PER SHARE (in dollars per share)	$ 0.54	$ 0.79	$ 0.91
WEIGHTED AVERAGE SHARES
Basic (in shares)	59,128	58,899	58,765
Diluted (in shares)	59,931	69,348	68,356
Asset Impairment Charges	$ 39,075	$ 0	$ 0