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Significant Accounting Policies (Components Of Investments) (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
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Significant Accounting Policies [Abstract] |  |  |
Equity method investments | [1] | $ 22 | $ 23
Investment in equity securities at adjusted cost | [2] | 5 | 25
Investments in equity securities at fair value |  | 36 |
Investments in exchange memberships and equity securities of certain exchanges |  | 3 | 5
Total investments |  | $ 66 | $ 53
[1] | The Company’s share of income or losses is included in other income in the consolidated statements of comprehensive income.
[2] | These investments do not qualify for equity method of accounting and the dividends received are included in other income in the consolidated statements of comprehensive income.

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- Definition Investments that are measured at adjusted cost since they do not have a readily determinable fair value. Adjusted cost represents the historical cost, less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. + References No definition available. + Details
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- Definition Total Investments + References No definition available. + Details
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- References No definition available. + Details
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- Definition Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments. + References No definition available. + Details
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- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 25 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8813-108599 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740 + Details
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