Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of investments in marketable securities

Our investments in marketable securities as of December 31, 2017 and 2016 consisted of the following:



	2017				2016
(millions)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Corporate debt securities	$	68	$	68	$	69	$	69
U.S. government and agency debt securities	6		6		14		14
Asset-backed debt securities	11		11		2		2
Certificates of deposit	13		13		6		6
Municipal debt securities	1		1		—		—
Total marketable securities	$	99	$	99	$	91	$	91

Schedule of contractual maturities of marketable securities

Contractual maturities of marketable securities as of December 31, 2017 were as follows:



(millions)	Amortized Cost		Fair Value
Due in 1 year or less	$	62	$	62
Due in 1-5 years	37		37
Total marketable securities	$	99	$	99

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

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