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Fair Value Measurements (Details) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Dec. 31, 2020 USD ($) investmentSecurity | Sep. 30, 2020 company | Dec. 31, 2020 USD ($) | Mar. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Investments in equity securities | $ 267,000,000 |  | $ 267,000,000 | $ 170,000,000
Number of companies in which equity securities were converted into public common stock | company |  | 3 |  |
Number of investments that experienced transaction that resulted in change in observable price of those securities | investmentSecurity | 2 |  |  |
Unrealized gain (loss) on equity investments | $ 28,000,000 |  | 87,000,000 |
Recurring | Fair value, inputs, level 2 |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Carrying amount of liabilities | 7,200,000,000 |  | 7,200,000,000 | 7,400,000,000
Estimated fair values of liabilities | 8,000,000,000.0 |  | 8,000,000,000.0 | 7,800,000,000
Recurring | Fair value, inputs, level 1 |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Investments in money market funds | 123,000,000 |  | 123,000,000 | 2,000,000,000.0
Nonrecurring |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Liabilities measured at fair value | $ 0 |  | $ 0 | $ 0

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- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References No definition available. + Details
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- Definition Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611 + Details
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