COMMITMENTS (DETAILS) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 carriers	Jun. 30, 2012	Jun. 30, 2013 carriers	Jun. 30, 2012
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Rent Expense	$ 83	$ 68	$ 153	$ 138
Airline, Capacity Purchase Arrangements, Carriers	3		3
Airline, Capacity Purchase Arrangements, Percent	100.00%		100.00%
Aircraft Commitments [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2013	205		205
2014	414		414
2015	259		259
2016	221		221
2017	329		329
Thereafter	1,456		1,456
Total	2,884		2,884
Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2013	19		19
2014	38		38
2015	31		31
2016	18		18
2017	19		19
Thereafter	8		8
Total	133		133
Engine Maintenance [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Remainder of 2013	6		6
2014	10		10
2015	10		10
2016	0		0
2017	0		0
Thereafter	0		0
Total	26		26
Aircraft Leases [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Operating Leases, Number of Units	63		63
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2013	44		44
2014	126		126
2015	105		105
2016	82		82
2017	51		51
Thereafter	79		79
Total	487		487
Facility Leases [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remainder of 2013	21		21
2014	41		41
2015	30		30
2016	22		22
2017	17		17
Thereafter	126		126
Total	$ 257		$ 257
B737 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft)	67		67
Options to Purchase Additional (in Aircraft)	69		69
B737-900ER [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft)	30		30
B737 MAX [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft)	37		37
Q400 [Member]
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
Committed to Purchase (in Aircraft)	3		3
Options to Purchase Additional (in Aircraft)	7		7
Assets Leased to Others [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Operating Leases, Number of Units	11		11
Non Operating Aircraft [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Operating Leases, Number of Units	14		14