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Fair Value Measurements - Investments Held in Trusts (Details) - USD ($) $ in Millions | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Short-term cash investments | $ 753 | $ 751
Short-term cash investments held for sale | 751 | 747
Debt securities held for sale | 124 | 135
Debt securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Cost Basis | 405 | 403
Unrealized Gains | 8 | 9
Unrealized Losses | (16) | (11)
Fair Value | $ 397 | $ 401

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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=118939692&loc=d3e27161-111563 + Details
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