Marketable Securities (current and non-current) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Marketable securities
Current marketable securities	$ 539	$ 380
Non-current marketable securities	46	37
Total marketable securities	585	417
Corporate debt securities
Marketable securities
Current marketable securities	16
Commercial paper
Marketable securities
Current marketable securities	510	366
Certificates of deposit/time deposits
Marketable securities
Current marketable securities	10	10
U.S. municipal securities
Marketable securities
Current marketable securities	3	3
Non-current marketable securities	$ 46	37
Asset-backed securities
Marketable securities
Current marketable securities		$ 1

Amount of investment in marketable security.

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