Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
REVENUES	$ 377,794	$ 334,576	$ 767,071	$ 682,759
OPERATING EXPENSES
Salaries, wages and benefits	119,503	97,850	245,034	197,191
Fuel	36,787	34,168	80,586	69,118
Maintenance, materials and repairs	43,704	39,467	85,381	84,005
Depreciation and amortization	68,291	63,266	137,633	125,903
Travel	17,315	20,937	38,972	41,035
Contracted ground and aviation services	13,546	14,531	27,895	30,129
Rent	5,198	3,984	8,684	7,737
Landing and ramp	2,772	2,391	5,517	5,439
Insurance	2,508	1,857	4,176	3,768
Other Cost and Expense, Operating	15,738	18,643	30,954	34,051
Transaction fees	0	0	0	373
Operating Expenses	354,616	297,094	694,086	598,749
OPERATING INCOME	23,178	37,482	72,985	84,010
OTHER INCOME (EXPENSE)
Interest income	12	81	124	177
Non-service component of retiree benefit costs	2,898	(2,351)	5,796	(4,702)
Non-service component of retiree benefit gains (costs)	(16,045)	(16,804)	(32,368)	(34,194)
Net loss on financial instruments	(109,723)	(35,886)	(2,679)	(31,386)
Other Nonoperating Income (Expense)	(129,371)	(60,958)	(38,404)	(79,919)
EARNINGS (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(106,193)	(23,476)	34,581	4,091
INCOME TAX (EXPENSE) BENEFIT		(3,156)	(6,010)	(8,089)
EARNINGS (LOSS) FROM CONTINUING OPERATIONS	(105,162)	(26,632)	28,571	(3,998)
EARNINGS FROM DISCONTINUED OPERATIONS, NET OF TAXES	236	31	4,008	62
NET EARNINGS (LOSS)	$ (104,926)	$ (26,601)	$ 32,579	$ (3,936)
BASIC EARNINGS PER SHARE
Basic earnings per share from continuing operations (in dollars per share)	$ (1.78)	$ (0.45)	$ 0.48	$ (0.07)
Discontinued operations (in dollars per share)	0.01	0	0.07	0
TOTAL BASIC EARNINGS PER SHARE (in dollars per share)	(1.77)	(0.45)	0.55	(0.07)
DILUTED EARNINGS PER SHARE
Diluted earnings per share from continuing operations (in dollars per share)	(1.78)	(0.45)	0.14	(0.07)
Discontinued operations (in dollars per share)	0.01	0	0.05	0
TOTAL DILUTED NET EARNINGS PER SHARE (in dollars per share)	$ (1.77)	$ (0.45)	$ 0.19	$ (0.07)
WEIGHTED AVERAGE SHARES
Basic (in shares)	59,130	58,909	59,085	58,874
Diluted (in shares)	59,130	58,909	68,104	58,874
Asset Impairment Charges	$ 39,075	$ 0	$ 39,075	$ 0
Income Tax (Expense) Benefit, Continuing Operations, Government Grants	(9,821)	0	(9,821)	0
Significant Reconciling Items [Member]
OTHER INCOME (EXPENSE)
Non-service component of retiree benefit gains (costs)	(681)	(903)	(1,336)	(1,683)
Loss from non-consolidated affiliates	$ (6,513)	$ (5,998)	$ (9,277)	$ (9,814)