Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
REVENUES	$ 404,146	$ 366,073	$ 1,171,217	$ 1,048,832
OPERATING EXPENSES
Salaries, wages and benefits	128,608	110,706	373,642	307,897
Fuel	36,202	41,193	116,788	110,311
Maintenance, materials and repairs	48,767	41,496	134,148	125,501
Depreciation and amortization	67,974	64,149	205,607	190,052
Travel	20,254	25,366	59,226	66,401
Contracted ground and aviation services	19,840	17,190	47,735	47,319
Rent	5,137	4,123	13,821	11,860
Landing and ramp	3,378	2,539	8,895	7,978
Insurance	3,119	1,833	7,295	5,601
Other Cost and Expense, Operating	18,623	16,712	49,577	50,763
Transaction fees	0	0	0	373
Operating Expenses	330,176	325,307	1,024,262	924,056
OPERATING INCOME	73,970	40,766	146,955	124,776
OTHER INCOME (EXPENSE)
Interest income	93	78	217	255
Non-service component of retiree benefit costs	2,897	(2,351)	8,693	(7,053)
Non-service component of retiree benefit gains (costs)	(15,440)	(16,712)	(47,808)	(50,906)
Net (loss) gain on financial instruments	(53,393)	91,952	(56,072)	60,566
Other Nonoperating Income (Expense)	(68,328)	70,322	(106,732)	(9,597)
EARNINGS (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	5,642	111,088	40,223	115,179
INCOME TAX EXPENSE		(6,003)	(17,397)	(14,092)
EARNINGS (LOSS) FROM CONTINUING OPERATIONS	(5,745)	105,085	22,826	101,087
EARNINGS FROM DISCONTINUED OPERATIONS, NET OF TAXES	154	243	4,162	305
NET EARNINGS (LOSS)	$ (5,591)	$ 105,328	$ 26,988	$ 101,392
BASIC EARNINGS PER SHARE
Basic earnings per share from continuing operations (in dollars per share)	$ (0.10)	$ 1.78	$ 0.39	$ 1.72
Discontinued operations (in dollars per share)	0.01	0.01	0.07	0
TOTAL BASIC EARNINGS PER SHARE (in dollars per share)	(0.09)	1.79	0.46	1.72
DILUTED EARNINGS PER SHARE
Diluted earnings per share from continuing operations (in dollars per share)	(0.10)	0.19	0.38	0.43
Discontinued operations (in dollars per share)	0.01	0.01	0.07	0
TOTAL DILUTED NET EARNINGS PER SHARE (in dollars per share)	$ (0.09)	$ 0.20	$ 0.45	$ 0.43
WEIGHTED AVERAGE SHARES
Basic (in shares)	59,146	58,919	59,106	58,889
Diluted (in shares)	59,146	68,718	59,863	69,382
Asset Impairment Charges	$ 0	$ 0	$ 39,075	$ 0
Income Tax (Expense) Benefit, Continuing Operations, Government Grants	(21,726)	0	(31,547)	0
Significant Reconciling Items [Member]
OTHER INCOME (EXPENSE)
Non-service component of retiree benefit gains (costs)	(797)	(610)	(2,133)	(2,293)
Loss from non-consolidated affiliates	$ (2,485)	$ (2,645)	$ (11,762)	$ (12,459)