COMMITMENTS AND CONTINGENCIES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Aircrafts		Dec. 31, 2010
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	127	[1]
Firm - 737NG 800 (in units)	73
Options-737NG (in units)	92
Leased-737NG 800 (in units)	5	[2]
Firm-737MAX (in units)	150	[3]
Options-737MAX (in units)	150
Total	597
Commitment (in dollars)	$ 12,621	[4]
Contingencies: [Abstract]
Municipal Bonds Issued	310
Expected total LFMP cost	519
Construction obligation	202		86
2012 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	28
Options-737NG (in units)	0
Leased-737NG 800 (in units)	5
Firm-737MAX (in units)	0
Options-737MAX (in units)	0
Total	33
Commitment (in dollars)	952
2013 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	41
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	0
Options-737MAX (in units)	0
Total	41
Commitment (in dollars)	1,188
2014 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	35
Firm - 737NG 800 (in units)	4
Options-737NG (in units)	15
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	0
Options-737MAX (in units)	0
Total	54
Commitment (in dollars)	1,151
2015 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	36
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	12
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	0
Options-737MAX (in units)	0
Total	48
Commitment (in dollars)	1,186
2016 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	31
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	12
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	0
Options-737MAX (in units)	0
Total	43
Commitment (in dollars)	1,157
2017 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	15
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	25
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	4
Options-737MAX (in units)	0
Total	44
Commitment (in dollars)	905
2018 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	10
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	28
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	15
Options-737MAX (in units)	0
Total	53
Commitment (in dollars)	1,126
2019 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	33
Options-737MAX (in units)	0
Total	33
Commitment (in dollars)	1,461
2020 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	34
Options-737MAX (in units)	0
Total	34
Commitment (in dollars)	1,184
2021 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	34
Options-737MAX (in units)	18
Total	52
Commitment (in dollars)	1,214
2022 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	30
Options-737MAX (in units)	19
Total	49
Commitment (in dollars)	1,097
2023 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	0
Options-737MAX (in units)	23
Total	23
Commitment (in dollars)	0
2024 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	0
Options-737MAX (in units)	23
Total	23
Commitment (in dollars)	0
Through 2027 [Member]
Long-term Purchase Commitment [Line Items]
Firm - 737NG 700 (in units)	0
Firm - 737NG 800 (in units)	0
Options-737NG (in units)	0
Leased-737NG 800 (in units)	0
Firm-737MAX (in units)	0
Options-737MAX (in units)	67
Total	67
Commitment (in dollars)	$ 0

[1] (a) The Company has flexibility to substitute 737-800s or 737-600s in lieu of 737-700 firm orders.

[2] (b) New delivery leased aircraft.

[3] (c) The Company has flexibility to accept MAX 7 or MAX 8 deliveries.

[4] (d) Firm orders from Boeing. The Company has flexibility as to the timing for certain of the firm orders in 2013 through 2017,but has classified the amounts in the earliest year they could be considered a commitment.