COMMITMENTS (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) aircraft carriers	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) aircraft carriers	Jun. 30, 2014 USD ($)
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Capacity purchase arrangements (carriers) | carriers	3		3
Capacity purchase arrangements (percent)	100.00%		100.00%
Rent expense	$ 67	$ 66	$ 140	$ 141
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2015	133		133
2016	604		604
2017	548		548
2018	428		428
2019	372		372
Thereafter	650		650
Total	2,735		2,735
Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2015	31		31
2016	67		67
2017	58		58
2018	60		60
2019	64		64
Thereafter	623		623
Total	903		903
Aircraft Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2015	27		27
2016	111		111
2017	93		93
2018	78		78
2019	67		67
Thereafter	345		345
Total	721		721
Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2015	50		50
2016	99		99
2017	94		94
2018	44		44
2019	42		42
Thereafter	212		212
Total	$ 541		$ 541
B-737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft	76		76
Options to Purchase Additional (in Aircraft) | aircraft	46		46
B737-900ER [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft	39		39
B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft	37		37
Q400 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft) | aircraft	2		2
Options to Purchase Additional (in Aircraft) | aircraft	5		5
CRJ-700 [Member] | Aircraft Leases [Member] | Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under capacity purchase agreement | aircraft	2		2
Operating Aircraft [Member] | CRJ-700 [Member] | Aircraft Leases [Member] | Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under capacity purchase agreement | aircraft	8		8
Operating Aircraft [Member] | E-175 [Domain] | Aircraft Leases [Member] | Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under capacity purchase agreement | aircraft	8		8
Number of aircraft under operating lease (in Aircraft) | aircraft	3		3
Operated by Skywest [Member] | B-737 [Member] | Aircraft Leases [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under operating lease (in Aircraft) | aircraft	28		28
Operated by Skywest [Member] | Q400 [Member] | Aircraft Leases [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under operating lease (in Aircraft) | aircraft	15		15
Operated by Skywest [Member] | CRJ-700 [Member] | Aircraft Leases [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under operating lease (in Aircraft) | aircraft	6		6
Operated by Skywest [Member] | E-175 [Domain] | Aircraft Leases [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under operating lease (in Aircraft) | aircraft	15		15
Number of additional aircraft that could be leased (in aircraft) | aircraft	16		16
Operated by Skywest [Member] | Operating Aircraft [Member] | CRJ-700 [Member] | Aircraft Leases [Member] | Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under capacity purchase agreement | aircraft	6		6
Subleased and Operated by Other Carrier [Member] | Non Operating Aircraft [Member] | CRJ-700 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Number of aircraft under operating lease (in Aircraft) | aircraft	8		8