Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-8957
Entity Registrant Name	ALASKA AIR GROUP, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	91-1292054
Entity Address, Address Line One	19300 International Boulevard
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98188
City Area Code	206
Local Phone Number	392-5040
Title of 12(b) Security	Common Stock, $0.01 Par Value
Security Exchange Name	NYSE
Trading Symbol	ALK
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		124,226,396
Entity Public Float			$ 4.5
Amendment Flag	false
Document Fiscal Year Focus	2020
Entity Central Index Key	0000766421
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
ICFR Auditor Attestation Flag	true