Label	Element	Value
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	alk_TaxCutsandJobsActReclassificationfromAOCItoRetainedEarningsTaxEffect	$ 0
AOCI Attributable to Parent [Member]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	alk_TaxCutsandJobsActReclassificationfromAOCItoRetainedEarningsTaxEffect	(62,000,000)
Retained Earnings [Member]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	alk_TaxCutsandJobsActReclassificationfromAOCItoRetainedEarningsTaxEffect	$ 62,000,000