OPERATING SEGMENT INFORMATION (Tables) - USD ($)
$ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2023

Jun. 30, 2022

Jun. 30, 2023

Jun. 30, 2022

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

Operating segment information is as follows (in millions):

	Three Months Ended June 30, 2023
	Mainline		Regional		Horizon		Consolidating & Other(a)		Air Group Adjusted(b)			Special Items(c)		Consolidated
Operating Revenue
Passenger revenue	$	2,228	$	370	$	—	$	—	$	2,598		$	—	$	2,598
CPA revenue	—		—		92		(92)		—			—		—
Mileage Plan other revenue	158		12		—		—		170			—		170
Cargo and other revenue	67		—		—		3		70			—		70
Total Operating Revenue	2,453		382		92		(89)		2,838			—		2,838
Operating Expenses
Operating expenses, excluding fuel	1,468		279		87		(92)		1,742			186		1,928
Fuel expense	490		81		—		1		572			1		573
Total Operating Expenses	1,958		360		87		(91)		2,314			187		2,501
Non-operating Income (Expense)	3		—		(10)		1		(6)			(6)		(12)
Income (Loss) Before Income Tax	$	498	$	22	$	(5)	$	3	$	518		$	(193)	$	325
Pretax Margin									18.3		%			11.5		%
	Three Months Ended June 30, 2022
	Mainline		Regional		Horizon		Consolidating & Other(a)		Air Group Adjusted(b)			Special Items(c)		Consolidated
Operating Revenue
Passenger revenue	$	2,028	$	390	$	—	$	—	$	2,418		$	—	$	2,418
CPA revenue	—		—		101		(101)		—			—		—
Mileage Plan other revenue	159		16		—		—		175			—		175
Cargo and other revenue	64		—		—		1		65			—		65
Total Operating Revenue	2,251		406		101		(100)		2,658			—		2,658
Operating Expenses
Operating expenses, excluding fuel	1,262		289		98		(100)		1,549			146		1,695
Fuel expense	617		119		—		—		736			40		776
Total Operating Expenses	1,879		408		98		(100)		2,285			186		2,471
Non-operating Income (Expense)	3		—		(5)		—		(2)			—		(2)
Income (Loss) Before Income Tax	$	375	$	(2)	$	(2)	$	—	$	371		$	(186)	$	185
Pretax Margin									14.0		%			7.0		%

	Six Months Ended June 30, 2023
	Mainline		Regional		Horizon		Consolidating & Other(a)		Air Group Adjusted(b)			Special Items(c)		Consolidated
Operating Revenue
Passenger revenue	$	3,918	$	664	$	—	$	—	$	4,582		$	—	$	4,582
CPA revenue	—		—		170		(170)		—			—		—
Mileage Plan other revenue	301		23		—		—		324			—		324
Cargo and other revenue	124		—		—		4		128			—		128
Total Operating Revenue	4,343		687		170		(166)		5,034			—		5,034
Operating Expenses
Operating expenses, excluding fuel	2,858		535		171		(169)		3,395			250		3,645
Fuel expense	1,051		166		—		—		1,217			21		1,238
Total Operating Expenses	3,909		701		171		(169)		4,612			271		4,883
Non-operating Income (Expense)	(3)		—		(18)		2		(19)			(6)		(25)
Income (Loss) Before Income Tax	$	431	$	(14)	$	(19)	$	5	$	403		$	(277)	$	126
Pretax Margin									8.0		%			2.5		%
	Six Months Ended June 30, 2022
	Mainline		Regional		Horizon		Consolidating & Other(a)		Air Group Adjusted(b)			Special Items(c)		Consolidated
Operating Revenue
Passenger revenue	$	3,271	$	658	$	—	$	—	$	3,929		$	—	$	3,929
CPA revenue	—		—		195		(195)		—			—		—
Mileage Plan other revenue	259		28		—		—		287			—		287
Cargo and other revenue	121		—		—		2		123			—		123
Total Operating Revenue	3,651		686		195		(193)		4,339			—		4,339
Operating Expenses
Operating expenses, excluding fuel	2,456		551		197		(194)		3,010			221		3,231
Fuel expense	998		192		—		—		1,190			(67)		1,123
Total Operating Expenses	3,454		743		197		(194)		4,200			154		4,354
Non-operating Income (Expense)	4		—		(10)		—		(6)			—		(6)
Income (Loss) Before Income Tax	$	201	$	(57)	$	(12)	$	1	$	133		$	(154)	$	(21)
Pretax Margin									3.1		%			(0.5)		%

(a)Includes consolidating entries, Air Group parent company, McGee Air Services, and other immaterial business units.

(b)The Air Group Adjusted column represents the financial information that is reviewed by management to assess performance of operations and determine capital allocation and excludes certain charges.

(c)Includes special items and mark-to-market fuel hedge accounting adjustments.

Total assets were as follows (in millions):

	June 30, 2023		December 31, 2022
Mainline	$	20,311	$	19,733
Horizon	1,285		1,157
Consolidating & Other	(6,767)		(6,704)
Consolidated	$	14,829	$	14,186

Nonoperating Income (Expense)

$ (12)

$ (2)

$ (25)

$ (6)

Interest income

22

11

39

18

Operating Expenses, Excluding Fuel

1,928

1,695

3,645

3,231

Economic fuel

573

776

1,238

1,123

Operating Expenses

2,501

2,471

4,883

4,354

Income (Loss) Before Income Tax

$ 325

$ 185

$ 126

$ (21)

Pretax Margin, GAAP

11.50%

7.00%

2.50%

(0.50%)

Pretax Margin, Adjusted

18.30%

14.00%

8.00%

3.10%