Airline, Capacity Purchase Arrangements, Carriers

No definition available.

Name:	alk_AirlineCapacityPurchaseArrangementsCarriers
Namespace Prefix:	alk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Airline, Capacity Purchase Arrangements, Percent

+ References

No definition available.

+ Details

Name:	alk_AirlineCapacityPurchaseArrangementsPercent
Namespace Prefix:	alk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Property Subject to or Available for Operating Lease, Number of Optional Additional Units

+ References

No definition available.

+ Details

Name:	alk_PropertySubjecttoorAvailableforOperatingLeaseNumberofOptionalAdditionalUnits
Namespace Prefix:	alk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required, Number Deferred

+ References

No definition available.

+ Details

Name:	alk_UnrecordedUnconditionalPurchaseObligationMinimumQuantityRequiredNumberDeferred
Namespace Prefix:	alk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Unrecorded Unconditional Purchase Obligation, Option to Cancel

+ References

No definition available.

+ Details

Name:	alk_UnrecordedUnconditionalPurchaseObligationOptiontoCancel
Namespace Prefix:	alk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Unrecorded Unconditional Purchase Obligation, Option to Purchase Additional

+ References

No definition available.

+ Details

Name:	alk_UnrecordedUnconditionalPurchaseObligationOptiontoPurchaseAdditional
Namespace Prefix:	alk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

Name:	us-gaap_LeaseAndRentalExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsRemainderOfFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The number of units (items of property) under operating lease arrangements.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseNumberOfUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationDueInRemainderOfFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum number of units that must be purchased, in connection with an unconditional purchase obligation that has not been recognized for financial reporting purposes.

+ References

No definition available.

+ Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationMinimumQuantityRequired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis=us-gaap_CapitalAdditionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis=us-gaap_CapacityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=alk_AircraftMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=us-gaap_B737Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=alk_B737900ErMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=us-gaap_B737MaxMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=us-gaap_A320NeoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=alk_E175Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAxis=us-gaap_PropertySubjectToOperatingLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=alk_AirbusMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=alk_Q400Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAxis=us-gaap_PropertyAvailableForOperatingLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AircraftTypeAxis=alk_A321neoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseArrangementTypeAxis=alk_CapacityPurchaseAgreementwithSkyWestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=alk_AircraftMaintenanceDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=alk_AircraftMaintenanceandPartsManagementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

COMMITMENTS (Details) $ in Millions	3 Months Ended		9 Months Ended
COMMITMENTS (Details) $ in Millions	Sep. 30, 2017 USD ($) aircraft carriers	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) aircraft carriers	Sep. 30, 2016 USD ($)
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Rent Expense	$ 145	$ 82	$ 406	$ 226
Capacity purchase arrangements (carriers) \| carriers	3		3
Capacity purchase arrangements	100.00%		100.00%
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2017	$ 168		$ 168
2018	956		956
2019	806		806
2020	352		352
2021	273		273
Thereafter	355		355
Total	2,910		2,910
Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2017	21		21
2018	118		118
2019	151		151
2020	158		158
2021	165		165
Thereafter	1,250		1,250
Total	1,863		1,863
Aircraft Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2017	77		77
2018	342		342
2019	344		344
2020	317		317
2021	280		280
Thereafter	1,263		1,263
Total	2,623		2,623
Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2017	34		34
2018	73		73
2019	65		65
2020	63		63
2021	55		55
Thereafter	204		204
Total	$ 494		$ 494
B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) \| aircraft	48		48
Options to Purchase Additional (in Aircraft) \| aircraft	37		37
B737-900ER [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) \| aircraft	16		16
B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) \| aircraft	32		32
A-320-Neo [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Unrecorded Unconditional Purchase Obligation, Option to Cancel \| aircraft	30		30
E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) \| aircraft	23		23
Number Deferred (in Aircraft) \| aircraft	3		3
Options to Purchase Additional (in Aircraft) \| aircraft	30		30
Property Subject to Operating Lease [Member] \| B-737 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of units involved in lease contracts \| aircraft	10		10
Property Subject to Operating Lease [Member] \| Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of units involved in lease contracts \| aircraft	55		55
Property Subject to Operating Lease [Member] \| Q400 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of units involved in lease contracts \| aircraft	15		15
Property Subject to Operating Lease [Member] \| E175 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of units involved in lease contracts \| aircraft	21		21
Property Available for Operating Lease [Member] \| A321neo [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of optional additional units \| aircraft	8		8
Property Available for Operating Lease [Member] \| E175 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of optional additional units \| aircraft	14		14
Capacity Purchase Agreement with SkyWest [Member] \| E175 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of optional additional units \| aircraft	8		8
Aircraft Maintenance Deposits [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2017	$ 15		$ 15
2018	61		61
2019	65		65
2020	68		68
2021	63		63
Thereafter	90		90
Total	362		362
Aircraft Maintenance and Parts Management [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2017	8		8
2018	32		32
2019	35		35
2020	37		37
2021	40		40
Thereafter	0		0
Total	$ 152		$ 152