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Fair Value Measurements (Details 5) - USD ($) $ in Millions | Jun. 30, 2018 | Dec. 31, 2017
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Carrying Value |  |
Fair value and related carrying amounts of long-term debt and other long-term obligations |  |
Long-term debt and other long-term obligations | $ 17,650 | $ 19,425
Fair Value |  |
Fair value and related carrying amounts of long-term debt and other long-term obligations |  |
Long-term debt and other long-term obligations | $ 18,876 | $ 21,551

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