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Financial Instruments (Details) - USD ($) | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Short-Term Investments [Abstract] |  |
Short-term investments | $ 60,000,000 | $ 60,000,000
Short-term investments reclassified as other assets | 15,000,000 |
Transfers out of level 2 | 0 |
Fair Value of Debt Instruments [Abstract] |  |
Fair value of total debt | 29,500,000,000 | 27,200,000,000
Fair value of total debt in excess of (less than) carrying value | 1,600,000,000 | $ 2,000,000,000.0
Significant Other Observable Inputs (Level 2) [Member] | Time Deposits [Member] |  |
Short-Term Investments [Abstract] |  |
Short-term investments | $ 75,000,000 |

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