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Investments (Schedule Of Sources Of Net Investment Income) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Net Investment Income [Line Items] |  |  |
Gross investment income | $ 3,551 | $ 3,598 | $ 3,473
Investment expenses | (176) | (172) | (168)
Net investment income | 3,375 | 3,426 | 3,305
Amortization of Debt Issuance Costs and Discounts | (367) | (395) | (592)
The Chubb Corporation [Member] |  |  |
Net Investment Income [Line Items] |  |  |
Amortization of Debt Issuance Costs and Discounts | (116) | (161) | (248)
Fixed Maturities [Member] |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 3,321 | 3,385 | 3,128
Short-term investments |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 48 | 84 | 90
Other interest income [Member] |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 19 | 25 | 118
Equity securities |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 81 | 26 | 33
Other Investments [Member] |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | $ 82 | $ 78 | $ 104

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