Investments - Fair Values by Contractual Maturity (Details) - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
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| Investments, Debt and Equity Securities [Abstract] | ||
| Maturing in one year or less | $ 5,629 | $ 17,424 |
| Maturing after one year through three years | 2,304 | 3,356 |
| Maturing after three years through five years | 119 | 5,168 |
| Maturing after five years through ten years | 0 | 885 |
| Mortgage- and asset-backed securities | 182 | 1,891 |
| Total available-for-sale investments | $ 8,234 | $ 28,724 |
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- Definition Available-For Sale Securities, Debt Maturities, After One Through Three Years, Fair Value No definition available.
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- Definition Available-For-Sale Securities, Debt Maturities, After Three Through Five Years, Fair Value No definition available.
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount 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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