Investments Short-term investments (Details) - USD ($) $ in Millions |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Short-term Investments [Abstract] | ||
| Trading investment securities | $ 25 | $ 25 |
| Available-for-sale Securities, Current | 1,972 | 2,264 |
| Held-to-maturity Securities, Current | 745 | 40 |
| Other Marketable Securities, Current | 389 | 806 |
| Short-term Investments | $ 3,131 | $ 3,135 |
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- Definition Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of other investments not classified as trading, available-for-sale or held-to-maturity, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- References No definition available.
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- Definition Fair value of investments in trading equity securities and other forms of trading securities that provide ownership interests. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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