EMPLOYEE BENEFIT PLANS  - Status Of Qualified Defined-Benefit Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Plan
Projected benefit obligation (PBO)
Beginning of year	$ 2,183	$ 2,079
Acquisition impact	333	0
Service cost	28	29
Interest cost	113	108	$ 65
Actuarial (gain)/loss	(86)	83
Benefits paid	(109)	(116)
End of year	2,462	2,183	2,079
Plan assets at fair value
Beginning of year	2,023	1,894
Acquisition impact	290	0
Actual return on plan assets	72	245
Pension contribution	31	0
Benefits paid	(109)	(116)
End of year	2,307	2,023	$ 1,894
Funded status (unfunded)	$ (155)	$ (160)
Percent funded	94.00%	93.00%
Postretirement Medical Benefits
Plan assets at fair value
End of year	$ 48
Funded status (unfunded)	(111)
Postretirement Medical Benefits | Alaska Air Group
Projected benefit obligation (PBO)
Beginning of year	98
End of year	93	$ 98
Postretirement Medical Benefits | Hawaiian Holdings, Inc.
Projected benefit obligation (PBO)
End of year	$ 159