Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

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

The table below segregates all financial assets 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 December 31, 2015 Using
	As of December 31, 2015			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs			Significant Unobservable Inputs		Balance Sheet Classification
				(Level 1)		(Level 2)			(Level 3)
Financial Assets:
Recurring fair value measurements:
Money market funds	$	1,613		$	1,613	$	—		$	—	Cash and cash equivalents
Foreign government treasury bills	34			34		—			—		Cash and cash equivalents
Foreign currency forward contracts not designated as hedges	11			—		11			—		Other current assets
Auction rate securities ("ARS")	9			—		—			9		Long-term investments
Total recurring fair value measurements	$	1,667		$	1,647	$	11		$	9
Financial Liabilities:
Foreign currency forward contracts designated as hedges	$	(4	)	$	—	$	(4	)	$	—	Accrued expenses and other liabilities

			Fair Value Measurements at December 31, 2014 Using
	As of December 31, 2014		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Balance Sheet Classification
			(Level 1)		(Level 2)		(Level 3)
Financial Assets:
Recurring fair value measurements:
Money market funds	$	4,475	$	4,475	$	—	$	—	Cash and cash equivalents
Foreign government treasury bills	40		40		—		—		Cash and cash equivalents
ARS	9		—		—		9		Long-term investments
Total recurring fair value measurements	$	4,524	$	4,515	$	—	$	9