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Investments, Contract Maturity of Available-for-Sale Securities (Details) | 12 Months Ended
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Dec. 31, 2018 Company
Contract Maturity of Available-for-Sale Securities [Abstract] |
One year or less | 77.00%
After one year but within two years | 20.00%
After two years but within three and one half years | 3.00%
Total | 100.00%
Percentage of available-for-sale securities with a maturity of less than two years | 97.00%
Maximum contract maturity period, range 1 | 1 year
Maximum contract maturity period, range 2 | 2 years
Maximum contract maturity period, range 3 | 3 years 6 months
Ownership Interests in Private and Public Companies [Abstract] |
Number of privately-held companies in which there is an equity ownership interest of less than 20% | 4
Number of publicly-held companies in which there is an equity ownership interest of less than 20% | 2

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- Definition The percentage of available-for-sale debt securities that mature beyond one year but within two years of the balance sheet date. + References No definition available. + Details
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- Definition The percentage of available-for-sale debt securities that mature beyond two years but within three and one-half years of the balance sheet date. + References No definition available. + Details
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- Definition The aggregate percentage of all available-for-sale debt securities, regardless of maturity. + References No definition available. + Details
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- Definition The percentage of available-for-sale debt securities that mature within one year of the balance sheet date. + References No definition available. + Details
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- Definition The percentage of available-for-sale debt securities that mature within two years of the balance sheet date. + References No definition available. + Details
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- Definition The maximum contract maturity period for the first range of available-for-sale securities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition The maximum contract maturity period for the second range of available-for-sale securities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition The maximum contract maturity period for the third range of available-for-sale securities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition Number of privately-held companies, in which the entity has an equity ownership interest of less than 20%, with which it conducts business. These are accounted for under the cost method. + References No definition available. + Details
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- Definition Number of publicly-held companies, in which the entity has an equity ownership interest of less than 20%, with which it conducts business. These are accounted for at fair value. + References No definition available. + Details
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