FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]

Fair values of financial instruments on the consolidated balance sheet (in millions):

December 31, 2016	Level 1		Level 2			Total
Assets
Marketable securities
U.S. government and agency securities	$	287	$	—		$	287
Foreign government bonds	—		36			36
Asset-backed securities	—		138			138
Mortgage-backed securities	—		89			89
Corporate notes and bonds	—		691			691
Municipal securities	—		11			11
Derivative instruments
Fuel hedge contracts—call options	—		20			20
Liabilities
Derivative instruments
Interest rate swap agreements	—		(5		)	(5		)

December 31, 2015	Level 1		Level 2			Total
Assets
Marketable securities
U.S. government and agency securities	$	253	$	—		$	253
Foreign government bonds	—		31			31
Asset-backed securities	—		130			130
Mortgage-backed securities	—		116			116
Corporate notes and bonds	—		708			708
Municipal securities	—		17			17
Derivative instruments
Fuel hedge contracts—call options	—		4			4
Liabilities
Derivative instruments
Interest rate swap agreements	—		(18		)	(18		)

Fixed-rate debt that is not carried at fair value on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt (in millions):

	2016		2015
Carrying amount	$	1,179	$	520
Fair value	1,199		557