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Financial Instruments - Information on Debt and Equity Securities (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, amortized cost | $ 89 | $ 1,768
Debt securities, gross unrealized gains | 0 | 17
Debt securities, gross unrealized losses | 0 | 0
Debt securities, fair value | 89 | 1,785
Publicly traded equity securities, fair value | 1,787 | 838
Total debt and publicly traded equity securities, fair value | 1,876 | 2,623
Unrealized net gains | 163 | 160
Commercial paper |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, amortized cost | 0 | 668
Debt securities, gross unrealized gains | 0 | 0
Debt securities, gross unrealized losses | 0 | 0
Debt securities, fair value | 0 | 668
Corporate notes and bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, amortized cost | 0 | 608
Debt securities, gross unrealized gains | 0 | 13
Debt securities, gross unrealized losses | 0 | 0
Debt securities, fair value | 0 | 621
U.S. government and agency securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, amortized cost | 84 | 266
Debt securities, gross unrealized gains | 0 | 3
Debt securities, gross unrealized losses | 0 | 0
Debt securities, fair value | 84 | 269
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, amortized cost | 0 | 226
Debt securities, gross unrealized gains | 0 | 1
Debt securities, gross unrealized losses | 0 | 0
Debt securities, fair value | 0 | 227
Foreign government bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, amortized cost | 5 | 0
Debt securities, gross unrealized gains | 0 | 0
Debt securities, gross unrealized losses | 0 | 0
Debt securities, fair value | 5 | 0
Fair Value, Measurements, Recurring | Corporate notes and bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, fair value | 0 | 621
Fair Value, Measurements, Recurring | U.S. government and agency securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, fair value | 0 | 209
Fair Value, Measurements, Recurring | Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, fair value | 0 | 227
Fair Value, Measurements, Recurring | Foreign government bonds |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt securities, fair value | 5 | 0
Fair Value, Measurements, Recurring | Publicly traded equity securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Publicly traded equity securities, fair value | $ 780 | $ 518

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
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- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
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