Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of Available-for-sale Securities Reconciliation [Table Text Block]

The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value of available-for-sale investments by type of security as of September 30, 2017 and December 31, 2016 were as follows:

	September 30, 2017
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
Commercial paper	$	33	$	—	$	—	$	33
Corporate bonds	471		1		—		472
Other government-related obligations:
U.S.	5		—		—		5
Foreign	449		—		—		449
Bank certificates of deposit	27		—		—		27
Total available-for-sale debt securities	$	985	$	1	$	—	$	986
Equity securities	—		1		—		1
Total available-for-sale securities	$	985	$	2	$	—	$	987

	December 31, 2016
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Commercial paper	$	114	$	—	$	—		$	114
Corporate bonds	124		—		(1		)	123
Municipal bonds	91		—		—			91
Other government-related obligations:
U.S.	28		—		—			28
Foreign	73		—		(1		)	72
Bank certificates of deposit	5		—		—			5
Total available-for-sale debt securities	$	435	$	—	$	(2	)	$	433
Equity securities	—		1		—			1
Total available-for-sale securities	$	435	$	1	$	(2	)	$	434

Available-for-sale Securities by Balance Sheet Location Classification [Table Text Block]

The fair values of available-for-sale securities by classification in the condensed consolidated balance sheet were as follows:

	September 30, 2017		December 31, 2016
Cash and cash equivalents	$	26	$	120
Marketable securities	961		314
	$	987	$	434

Investments Classified by Contractual Maturity Date [Table Text Block]

The fair values of available-for-sale debt securities as of September 30, 2017, by contractual maturity, are summarized as follows:

	September 30, 2017
Due in one year or less	$	493
Due after one year through three years	493
	$	986