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Financial Instruments - Information on Available-for-sale Investments (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 | Mar. 31, 2020 | Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items] |  |  |
Debt securities, amortized cost | $ 87 |  | $ 89
Debt securities, unrealized gains | 0 |  | 0
Debt securities, unrealized losses | 0 |  | 0
Debt securities, fair value | 87 |  | 89
Publicly traded equity securities, fair value | 1,596 |  | 1,787
Total debt and publicly traded equity securities, fair value | 1,683 |  | 1,876
Unrealized net losses (gains) | 181 | $ 4 |
U.S. government and agency securities |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Debt securities, amortized cost | 81 |  | 84
Debt securities, unrealized gains | 0 |  | 0
Debt securities, unrealized losses | 0 |  | 0
Debt securities, fair value | 81 |  | 84
Foreign government bonds |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Debt securities, amortized cost | 2 |  | 5
Debt securities, unrealized gains | 0 |  | 0
Debt securities, unrealized losses | 0 |  | 0
Debt securities, fair value | 2 |  | 5
Corporate notes and bonds |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Debt securities, amortized cost | 4 |  | 0
Debt securities, unrealized gains | 0 |  | 0
Debt securities, unrealized losses | 0 |  | 0
Debt securities, fair value | $ 4 |  | $ 0

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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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