Marketable Securities

6 Months Ended

Jun. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Marketable securities are classified as available-for-sale securities and reported at fair value, with unrealized gains and losses excluded from earnings and reported in "Accumulated other comprehensive loss", or AOCI, on our accompanying condensed consolidated balance sheets. Proceeds received from sales or maturities of marketable securities were as follows:



	Three months ended June 30,				Six months ended June 30,
(millions)	2017		2016		2017		2016
Proceeds received	$	31	$	103	$	53	$	187

Our investments in marketable securities consisted of the following:



	As of June 30, 2017				As of December 31, 2016
(millions)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Corporate debt securities	$	62	$	62	$	69	$	69
U.S. government and agency debt securities	10		10		14		14
Non-U.S. government debt securities	1		1		—		—
Asset-backed debt securities	8		8		2		2
Certificates of deposit	11		11		6		6
Total marketable securities	$	92	$	92	$	91	$	91

The realized and unrealized gains and losses for the three and six months ended June 30, 2017 and 2016 were immaterial. Cost basis for securities sold are determined on a first-in-first-out basis.

Contractual maturities of marketable securities as of June 30, 2017 were as follows:



(millions)	Amortized Cost		Fair Value
Due in 1 year or less	$	59	$	59
Due in 1-5 years	33		33
Total marketable securities	$	92	$	92

Actual maturities may differ from the contractual maturities because issuers of the securities may have the right to prepay them.