COMMITMENTS (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) aircraft carriers	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) aircraft carriers	Sep. 30, 2015 USD ($)	Oct. 11, 2016 aircraft
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Rent Expense	$ 82	$ 77	$ 226	$ 217
Capacity purchase arrangements (carriers) | carriers	3		3
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2016	$ 146		$ 146
2017	931		931
2018	724		724
2019	645		645
2020	334		334
Thereafter	397		397
Total	3,177		3,177
Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2016	17		17
2017	78		78
2018	81		81
2019	86		86
2020	92		92
Thereafter	746		746
Total	1,100		1,100
Aircraft [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2016	20		20
2017	99		99
2018	90		90
2019	82		82
2020	73		73
Thereafter	400		400
Total	764		764
Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2016	24		24
2017	91		91
2018	43		43
2019	43		43
2020	40		40
Thereafter	188		188
Total	$ 429		$ 429
B-737 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of lease contracts (aircraft) | aircraft	18		18
Q400 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of lease contracts (aircraft) | aircraft	15		15
E175 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft	33		33
Options to Purchase Additional (in Aircraft) | aircraft	30		30
Horizon [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Capacity purchase arrangements	100.00%		100.00%
Capacity Purchase Agreement with SkyWest [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of lease contracts (aircraft) | aircraft	16		16
Capacity Purchase Agreement with SkyWest [Member] | CRJ-700 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of lease contracts (aircraft) | aircraft	3		3
Capacity Purchase Agreement with SkyWest [Member] | E175 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of lease contracts (aircraft) | aircraft	13		13
Number of optional additional leases (aircraft) | aircraft	8		8
Subsequent Event [Member] | B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft					56
Options to Purchase Additional (in Aircraft) | aircraft					41
Subsequent Event [Member] | B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Unrecorded Unconditional Purchase Obligation, Quantity Deferred | aircraft					4
Committed to Purchase (in Aircraft) | aircraft					37
Subsequent Event [Member] | Boeing, 737-900ER [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Options to Purchase Additional, Exercised(in Aircraft) | aircraft					5
Committed to Purchase (in Aircraft) | aircraft					19