Fair Value Measurements - Summary of Fair Value and Carrying Value of Financial Assets and Liabilities (Footnotes) (Details) - USD ($) $ in Millions |
Sep. 30, 2019 |
Dec. 31, 2018 |
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| Fair Value Disclosures [Abstract] | ||
| Amortized cost of investments | $ 109 | $ 173 |
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References No definition available.
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