OPERATING SEGMENT INFORMATION (DETAILS) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Operating revenues
Mainline	$ 3,176.2		$ 2,763.4		$ 2,438.8
Regional	774.5		725.2		668.6
Passenger revenues	3,950.7		3,488.6		3,107.4
Segment Reporting Information, Intersegment Revenue	0		0		0
Freight and mail	108.7		106.2		95.9
Other - net	258.4		237.5		196.5
Total Operating Revenues	4,317.8		3,832.3		3,399.8
Operating expenses
Operating expenses, excluding fuel	2,571.2	[1]	2,459.8	[1]	2,474.3	[1]
Economic fuel	1,297.7	[2]	900.9	[2]	658.1	[2]
Total Operating Expenses	3,868.9		3,360.7		3,132.4
Nonoperating income (expense)
Interest income	21.9		29.4		32.6
Interest expense	(87.3)		(108.3)		(104.3)
Other	10.2		13.2		7.2
Nonoperating Income (Expense) Total	(55.2)		(65.7)		(64.5)
Income (loss) before income tax	393.7		405.9		202.9
Depreciation	246.9		230.5		219.2
Capital expenditures	387.4		185.3		438.4
Total assets	5,195.0		5,016.6
Air Group Adjusted [Member]
Operating revenues
Mainline	3,176.2	[3]	2,763.4	[3]	2,438.8	[3]
Regional	774.5	[3]	725.2	[3]	668.6	[3]
Passenger revenues	3,950.7	[3]	3,488.6	[3]	3,107.4	[3]
Segment Reporting Information, Intersegment Revenue	0		0		0
Freight and mail	108.7	[3]	106.2	[3]	95.9	[3]
Other - net	258.4	[3]	237.5	[3]	196.5	[3]
Total Operating Revenues	4,317.8	[3]	3,832.3	[3]	3,399.8	[3]
Operating expenses
Operating expenses, excluding fuel	2,532.3	[1],[3]	2,446.6	[1],[3]	2,438.5	[1],[3]
Economic fuel	1,267.6	[2],[3]	895.6	[2],[3]	746.9	[2],[3]
Total Operating Expenses	3,799.9	[3]	3,342.2	[3]	3,185.4	[3]
Nonoperating income (expense)
Interest income	21.9	[3]	29.4	[3]	32.6	[3]
Interest expense	(87.3)	[3]	(108.3)	[3]	(104.3)	[3]
Other	10.2	[3]	13.2	[3]	7.2	[3]
Nonoperating Income (Expense) Total	(55.2)	[3]	(65.7)	[3]	(64.5)	[3]
Income (loss) before income tax	462.7	[3]	424.4	[3]	149.9	[3]
Alaska Airlines [Member]
Nonoperating income (expense)
Depreciation	202.9	[4]	188.5	[4]	178.5	[4]
Capital expenditures	250.5	[4]	166.2	[4]	357.5	[4]
Total assets	4,803.3	[4]	4,610.2	[4]
Alaska Mainline [Member]
Operating revenues
Mainline	3,176.2		2,763.4		2,438.8
Regional	0		0		0
Passenger revenues	3,176.2		2,763.4		2,438.8
Segment Reporting Information, Intersegment Revenue	0		0		0
Freight and mail	104.6		101.9		91.5
Other - net	249.9		228.8		187.3
Total Operating Revenues	3,530.7		3,094.1		2,717.6
Operating expenses
Operating expenses, excluding fuel	2,015.4	[1]	1,916.9	[1]	1,910.9	[1]
Economic fuel	1,101.2	[2]	757.3	[2]	622.7	[2]
Total Operating Expenses	3,116.6		2,674.2		2,533.6
Nonoperating income (expense)
Interest income	23.9		34.8		38.6
Interest expense	(72.2)		(96.5)		(91.7)
Other	8.9		13.1		8.1
Nonoperating Income (Expense) Total	(39.4)		(48.6)		(45.0)
Income (loss) before income tax	374.7		371.3		139.0
Alaska Regional [Member]
Operating revenues
Mainline	0		0		0
Regional	774.5		330.6		286.7
Passenger revenues	774.5		330.6		286.7
Segment Reporting Information, Intersegment Revenue	0		0		0
Freight and mail	3.9		1.8		1.7
Other - net	0.5		0.1		1.1
Total Operating Revenues	778.9		332.5		289.5
Operating expenses
Operating expenses, excluding fuel	543.5	[1]	298.9	[1]	280.5	[1]
Economic fuel	166.4	[2]	0	[2]	0	[2]
Total Operating Expenses	709.9		298.9		280.5
Nonoperating income (expense)
Interest income	0		0		0
Interest expense	0		0		0
Other	0		0		0
Nonoperating Income (Expense) Total	0		0		0
Income (loss) before income tax	69.0		33.6		9.0
Horizon [Member]
Operating revenues
Mainline	0		0		0
Regional	0		394.5		381.9
Passenger revenues	0		394.5		381.9
Segment Reporting Information, Intersegment Revenue	369.4		274.4		261.7
Freight and mail	0.2		2.5		2.7
Other - net	8.0		8.6		8.1
Total Operating Revenues	377.6		680.0		654.4
Operating expenses
Operating expenses, excluding fuel	340.3	[1]	502.1	[1]	504.5	[1]
Economic fuel	0	[2]	138.3	[2]	124.2	[2]
Total Operating Expenses	340.3		640.4		628.7
Nonoperating income (expense)
Interest income	0.3		3.6		2.0
Interest expense	(17.2)		(20.5)		(20.1)
Other	1.3		0.1		0.1
Nonoperating Income (Expense) Total	(15.6)		(16.8)		(18.0)
Income (loss) before income tax	21.7		22.8		7.7
Depreciation	43.4		41.0		39.5
Capital expenditures	136.9		19.1		80.9
Total assets	846.5		747.2
Parent [Member]
Nonoperating income (expense)
Depreciation	0.6		1.0		1.2
Total assets	1,583.5		1,375.6
Intersegment Elimination [Member]
Operating revenues
Mainline	0		0		0
Regional	0		0.1		0
Passenger revenues	0		0.1		0
Segment Reporting Information, Intersegment Revenue	(369.4)		(274.4)		(261.7)
Freight and mail	0		0		0
Other - net	0		0		0
Total Operating Revenues	(369.4)		(274.3)		(261.7)
Operating expenses
Operating expenses, excluding fuel	(366.9)	[1]	(271.3)	[1]	(257.4)	[1]
Economic fuel	0	[2]	0	[2]	0	[2]
Total Operating Expenses	(366.9)		(271.3)		(257.4)
Nonoperating income (expense)
Interest income	(2.3)		(9.0)		(8.0)
Interest expense	2.1		8.7		7.5
Other	0		0		(1.0)
Nonoperating Income (Expense) Total	(0.2)		(0.3)		(1.5)
Income (loss) before income tax	(2.7)		(3.3)		(5.8)
Total assets	(2,038.3)		(1,716.4)
Special Charges [Member]
Operating revenues
Mainline	0		0		0
Regional	0		0		0
Passenger revenues	0		0		0
Segment Reporting Information, Intersegment Revenue	0		0		0
Freight and mail	0		0		0
Other - net	0		0		0
Total Operating Revenues	0		0		0
Operating expenses
Operating expenses, excluding fuel	38.9	[1]	13.2	[1]	35.8	[1]
Economic fuel	30.1	[2]	5.3	[2]	(88.8)	[2]
Total Operating Expenses	69.0		18.5		(53.0)
Nonoperating income (expense)
Interest income	0		0		0
Interest expense	0		0		0
Other	0		0		0
Nonoperating Income (Expense) Total	0		0		0
Income (loss) before income tax	$ (69.0)		$ (18.5)		$ 53.0

[1] Refer to Note 14 for a summary of special charges for each respective period.

[2] Represents adjustments to reflect the timing of gain or loss recognition resulting from mark-to-market fuel-hedge accounting.

[3] The adjusted column represents the financial information that is reviewed by management to assess performance of operations and determine capital allocations and does not include certain charges.

[4] a) There are no depreciation expenses, capital expenditures or assets associated with purchased capacity flying at Alaska.