Fair Value Measurements and Investments (Tables)

12 Months Ended

Dec. 31, 2017

Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The table below presents disclosures about the fair value of financial assets and liabilities measured at fair value on a recurring basis in the Company’s financial statements as of December 31 (in millions):


	2017								2016
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	1,482	$	1,482	$	—	$	—	$	2,179	$	2,179	$	—	$	—
Short-term investments:
Corporate debt		958		—		958		—		835		—		835		—
Asset-backed securities		753		—		753		—		792		—		792		—
Certificates of deposit placed through an account registry service (“CDARS”)		120		—		120		—		246		—		246		—
U.S. government and agency notes		113		—		113		—		140		—		140		—
Other fixed-income securities		188		—		188		—		54		—		54		—
Other investments measured at NAV		184		—		—		—		182		—		—		—
Restricted cash		109		109		—		—		124		124		—		—
Long-term investments:
Equity securities		99		99		—		—		—		—		—		—
Enhanced equipment trust certificates (“EETC”)		22		—		—		22		23		—		—		23

Carrying Values and Estimated Fair Values of Financial Instruments

The table below presents the carrying values and estimated fair values of financial instruments not presented in the tables above as of December 31 (in millions):


	Fair Value of Debt by Fair Value Hierarchy Level
	2017										2016
	Carrying Amount		Fair Value								Carrying Amount		Fair Value
			Total		Level 1		Level 2		Level 3				Total		Level 1		Level 2		Level 3
Long-term debt	$	13,268	$	13,787	$	—	$	10,115	$	3,672	$	10,767	$	11,055	$	—	$	8,184	$	2,871