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Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions | Mar. 31, 2025 | Dec. 31, 2024
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Available For Sale Securities [Abstract] |  |
Investment, Type [Extensible Enumeration] | Fixed Maturities [Member] | Fixed Maturities [Member]
Total available-for-sale, amortized cost | $ 1,467 | $ 1,391
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 5 | 5
Gross unrealized losses | (139) | (160)
Total available-for-sale, fair value | 1,333 | 1,236
U.S. Treasury And Government Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 508 | 500
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | (13) | (19)
Total available-for-sale, fair value | 495 | 481
US States And Political Subdivisions [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 109 | 110
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 2 | 2
Gross unrealized losses | (9) | (11)
Total available-for-sale, fair value | 102 | 101
Foreign Governments [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 9 | 12
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | (2) | (2)
Total available-for-sale, fair value | 7 | 10
Corporate Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 485 | 496
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 1 | 1
Gross unrealized losses | (98) | (106)
Total available-for-sale, fair value | 388 | 391
Residential Mortgage-Backed Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 123 | 127
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | (14) | (16)
Total available-for-sale, fair value | 109 | 111
Residential Mortgage-Backed Non-Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 13 | 36
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 1
Gross unrealized losses | (1) | (5)
Total available-for-sale, fair value | 12 | 32
Commercial Mortgage-Backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 15 | 7
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | 0 | 0
Total available-for-sale, fair value | 15 | 7
Collateralized Debt Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 58 | 71
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 1 | 1
Gross unrealized losses | 0 | 0
Total available-for-sale, fair value | 59 | 72
Other Asset-Backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 147 | 32
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 1 | 0
Gross unrealized losses | (2) | (1)
Total available-for-sale, fair value | $ 146 | $ 31

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 + Details
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