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Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
U S Treasury And Government [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | $ 541 | $ 782
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 5 | 54
Gross unrealized losses | (38) | (2)
Total available-for-sale, fair value | 508 | 834
US States And Political Subdivisions [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 173 | 140
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 2 | 27
Gross unrealized losses | (11) | 0
Total available-for-sale, fair value | 164 | 167
Foreign Governments [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 23 | 13
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 1
Gross unrealized losses | (3) | 0
Total available-for-sale, fair value | 20 | 14
Corporate Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 862 | 905
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 1 | 53
Gross unrealized losses | (148) | (5)
Total available-for-sale, fair value | 715 | 953
Residential Mortgage-Backed Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 217 | 190
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 3
Gross unrealized losses | (22) | (1)
Total available-for-sale, fair value | 195 | 192
Residential Mortgage-Backed Non-Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 96 | 80
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 3 | 12
Gross unrealized losses | (11) | 0
Total available-for-sale, fair value | 88 | 92
Commercial Mortgage-Backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 24 | 10
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | (1) | 0
Total available-for-sale, fair value | 23 | 10
Collateralized Debt Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 117 | 101
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | (5) | 0
Total available-for-sale, fair value | 112 | 101
Other Asset-Backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 110 | 95
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | (4) | (1)
Total available-for-sale, fair value | 106 | 94
Fixed Maturities [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 2,163 | 2,316
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 11 | 150
Gross unrealized losses | (243) | (9)
Total available-for-sale, fair value | $ 1,931 | $ 2,457

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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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563 + Details
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