FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value, Measurement Inputs, Disclosure

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



March 31, 2016	Level 1		Level 2			Total
Assets
Marketable securities
U.S. government and agency securities	$	412	$	—		$	412
Foreign government bonds	—		28			28
Asset-backed securities	—		154			154
Mortgage-backed securities	—		121			121
Corporate notes and bonds	—		754			754
Municipal securities	—		17			17
Total Marketable securities	412		1,074			1,486
Derivative instruments
Fuel hedge call options	—		8			8
Total Assets	412		1,082			1,494

Liabilities
Derivative instruments
Interest rate swap agreements	—		(22		)	(22		)
Total Liabilities	—		(22		)	(22		)



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 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) is as follows:



	March 31, 2016		December 31, 2015
Carrying amount	$	491	$	520
Fair value	529		557