INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

Deferred tax (assets) and liabilities comprise the following (in millions):

	2020		2019
Excess of tax over book depreciation	$	1,126	$	1,233
Intangibles - net	15		16
Operating lease assets	342		416
Other - net	106		58
Deferred tax liabilities	1,589		1,723
Mileage Plan™	(385)		(337)
Inventory obsolescence	(17)		(15)
Employee benefits	(215)		(179)
Net operating losses	(27)		(13)
Operating lease liabilities	(381)		(417)
Leasehold maintenance	(73)		—
Other - net	(103)		(48)
Deferred tax assets	(1,201)		(1,009)
Valuation allowance	19		1
Net deferred tax liabilities	$	407	$	715

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The components of income tax expense (benefit) are as follows (in millions): 

	2020		2019		2018
Current income tax expense (benefit):
Federal	$	(212)	$	26	$	(5)
State	(11)		13		9
Total current income tax expense (benefit)	(223)		39		4
Deferred income tax expense (benefit):
Federal	(246)		175		125
State	(47)		33		19
Total deferred income tax expense (benefit)	(293)		208		144
Income tax expense (benefit)	$	(516)	$	247	$	148

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	2020			2019			2018
Income (loss) before income tax	$	(1,840)		$	1,016		$	585
Expected tax expense (benefit)	(386)			213			123
Nondeductible expenses	9			9			9
State income tax expense (benefit)	(62)			36			21
Tax law changes	(93)			(9)			(7)
Valuation allowance	18			—			—
Other - net	(2)			(2)			2
Actual tax expense (benefit)	$	(516)		$	247		$	148
Effective tax rate	28.0		%	24.3		%	25.3		%

Summary of Income Tax Contingencies [Table Text Block]

The Company has identified its federal tax return and its state tax returns in Alaska, Oregon and California as “major” tax jurisdictions.  A summary of the Company's jurisdictions and the periods that are subject to examination are as follows:

Jurisdiction	Period
Federal	2007 to 2019
Alaska	2015 to 2019
California	2007 to 2019
Oregon	2003 to 2019

Certain tax years are open to the extent of net operating loss carryforwards.

Changes in the liability for gross unrecognized tax benefits during 2020, 2019 and 2018 are as follows (in millions):

	2020		2019		2018
Balance at January 1,	$	40	$	40	$	43
Additions related to prior years	1		—		1
Releases related to prior years	(1)		(1)		(4)
Additions related to current year activity	—		2		2
Releases due to settlements	(4)		—		(1)
Releases due to lapse of statute of limitations	(1)		(1)		(1)
Balance at December 31,	$	35	$	40	$	40