Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Fair value, assets measured on a recurring and/or non-recurring basis

The table below segregates all of our financial assets and liabilities that are measured at fair value on a recurring basis into the most appropriate level within the fair value hierarchy based on the inputs used to determine the fair value at the measurement date (amounts in millions):

				Fair Value Measurements at June 30, 2017 Using
	As of June 30, 2017			Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Balance Sheet Classification
Financial Assets:
Recurring fair value measurements:
Money market funds	$	2,925		$	2,925	$	—		$	—	Cash and cash equivalents
Foreign government treasury bills	47			47		—			—		Cash and cash equivalents
Total recurring fair value measurements	$	2,972		$	2,972	$	—		$	—
Financial liabilities:
Foreign currency forward contracts designated as hedges	$	(9	)	$	—	$	(9	)	$	—	Accrued expenses and other liabilities

			Fair Value Measurements at December 31, 2016 Using
	As of December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Balance Sheet Classification
Financial Assets:
Recurring fair value measurements:
Money market funds	$	2,921	$	2,921	$	—	$	—	Cash and cash equivalents
Foreign government treasury bills	38		38		—		—		Cash and cash equivalents
Foreign currency forward contracts designated as hedges	22		—		22		—		Other current assets
Auction rate securities ("ARS")	9		—		—		9		Other assets
Total recurring fair value measurements	$	2,990	$	2,959	$	22	$	9