Label	Element	Value
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	alk_TaxCutsandJobsActReclassificationfromAOCItoRetainedEarningsTaxEffect	$ 3,000,000
AOCI Attributable to Parent [Member]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	alk_TaxCutsandJobsActReclassificationfromAOCItoRetainedEarningsTaxEffect	0
Retained Earnings [Member]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	alk_TaxCutsandJobsActReclassificationfromAOCItoRetainedEarningsTaxEffect	$ 3,000,000
B-737 [Member] | Aircraft [Domain] | July 2020 EETC [Member]
Debt Instrument, Collateral	us-gaap_DebtInstrumentCollateral	42
E175 [Member] | Aircraft [Domain]
Debt Instrument, Collateral	us-gaap_DebtInstrumentCollateral	19