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Investments (Fair Value Below Amortized Cost of Gross Unrealized Losses for Fixed Maturity and Equity Securities) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2021 | Dec. 31, 2020
Gross unrealized losses with number of securities [Line Items] |  |
Document Period End Date | Mar. 31, 2021 |
Gross Unrealized Losses | $ 490 | $ 197
% of Total | 100.00% | 100.00%
Less than 20% |  |
Gross unrealized losses with number of securities [Line Items] |  |
Gross Unrealized Losses | $ 427 | $ 133
% of Total | 87.20% | 67.50%
20% or more for less than six months |  |
Gross unrealized losses with number of securities [Line Items] |  |
Gross Unrealized Losses | $ 28 | $ 42
% of Total | 5.70% | 21.30%
20% or more for six months or greater |  |
Gross unrealized losses with number of securities [Line Items] |  |
Gross Unrealized Losses | $ 35 | $ 22
% of Total | 7.10% | 11.20%

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- Definition Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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