FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2016

Fair Value Disclosures [Abstract]

Fair Value, Measurement Inputs, Disclosure

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

September 30, 2016	Level 1		Level 2			Total
Assets
Marketable securities
U.S. government and agency securities	$	332	$	—		$	332
Foreign government bonds	—		36			36
Asset-backed securities	—		154			154
Mortgage-backed securities	—		102			102
Corporate notes and bonds	—		767			767
Municipal securities	—		17			17
Total Marketable securities	332		1,076			1,408
Derivative instruments
Fuel hedge call options	—		16			16
Total Assets	332		1,092			1,424
Liabilities
Derivative instruments
Interest rate swap agreements	—		(20		)	(20		)
Total Liabilities	—		(20		)	(20		)

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
Total Marketable securities	253		1,002			1,255
Derivative instruments
Fuel hedge call options	—		4			4
Total Assets	253		1,006			1,259
Liabilities
Derivative instruments
Interest rate swap agreements	—		(18		)	(18		)
Total Liabilities	—		(18		)	(18		)

Fair Value, by Balance Sheet Grouping

Fixed-rate debt which is not carried at fair value on the consolidated balance sheet, has an estimated fair value of (in millions):

	September 30, 2016		December 31, 2015
Carrying amount	$	730	$	520
Fair value	759		557