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Financial Instruments and Risk Management - Summary of Securities That Were in Unrealized Loss Position (Detail) $ in Millions | Dec. 31, 2018 USD ($)
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Schedule of Available-for-sale Securities [Line Items] |
Fair Values, Less than 12 months | $ 0
Unrealized Losses, Less than 12 months | 0
Fair Values, More than 12 months | 330
Unrealized Losses, More than 12 months | (2)
Fair Values, Total | 330
Unrealized Losses, Total | (2)
U.S. Treasury Debt Securities [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Values, Less than 12 months | 0
Unrealized Losses, Less than 12 months | 0
Fair Values, More than 12 months | 330
Unrealized Losses, More than 12 months | (2)
Fair Values, Total | 330
Unrealized Losses, Total | $ (2)

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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. + References No definition available. + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References No definition available. + Details
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