Marketable Securities - Current and non-current (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Marketable Securities
Current marketable securities	$ 224	$ 98
Non-current marketable securities	34	43
Total marketable securities	258	141
Commercial paper
Marketable Securities
Current marketable securities	194	85
Certificates of deposit/time deposits
Marketable Securities
Current marketable securities	6	10
U.S. municipal securities
Marketable Securities
Current marketable securities	24	3
Non-current marketable securities	$ 34	$ 43

Amount of investment in marketable security.

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Amount of investment in marketable security, classified as current.

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Amount of investment in marketable security, classified as noncurrent.

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