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Investments (Schedule of Gains and Losses on Equity and Other Investments) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Gain (Loss) on Securities [Line Items] |  |  |
Net realized gains (losses) | $ (607) | $ (1,085) | $ 1,030
Unrealized gains (losses) recognized for securities still held at reporting date | 3,120 | (9,535) | (2,417)
Equity Securities [Member] |  |  |
Gain (Loss) on Securities [Line Items] |  |  |
Equity Securities, FV-NI, Realized Gain (Loss) | (38) | (230) | 662
Less: Net gains (losses) recognized from sales of securities | (68) | 409 | 157
Unrealized gains (losses) recognized for securities still held at reporting date | 30 | (639) | 505
Other Investments |  |  |
Gain (Loss) on Securities [Line Items] |  |  |
Net realized gains (losses) | (12) | 0 | 0
Less: Net gains (losses) recognized from sales of securities | 0 |  |
Unrealized gains (losses) recognized for securities still held at reporting date | (12) |  |
Equity securities and other investments [Member] |  |  |
Gain (Loss) on Securities [Line Items] |  |  |
Net realized gains (losses) | 20 | (261) | 773
Less: Net gains (losses) recognized from sales of securities | (68) | 409 | 157
Unrealized gains (losses) recognized for securities still held at reporting date | 88 | (670) | 616
Private equities |  |  |
Gain (Loss) on Securities [Line Items] |  |  |
Net realized gains (losses) | 70 | (31) | 111
Less: Net gains (losses) recognized from sales of securities | 0 | 0 | 0
Unrealized gains (losses) recognized for securities still held at reporting date | $ 70 | $ (31) | $ 111

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- Definition Amount of realized gain (loss) from sale 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 -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(3)(d)(1)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 321 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479536/321-10-50-4 + Details
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- Definition The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 + Details
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