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Available-for-Sale Debt Securities - Summary of the Balance Sheet Classification of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions | Jun. 30, 2020 | Dec. 31, 2019
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Available-for-Sale Debt Securities |  |
Available-for-sale debt securities | $ 14,935 | $ 16,500
Cash and cash equivalents |  |
Available-for-Sale Debt Securities |  |
Available-for-sale debt securities | 491 | 2,291
Short-term marketable securities |  |
Available-for-Sale Debt Securities |  |
Available-for-sale debt securities | 12,168 | 12,721
Long-term marketable securities |  |
Available-for-Sale Debt Securities |  |
Available-for-sale debt securities | $ 2,276 | $ 1,488

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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). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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