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Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | $ 2,316 | $ 2,360
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 150 | 184
Gross unrealized losses | (9) | (5)
Total available-for-sale, fair value | 2,457 | 2,539
U S Treasury And Government [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 782 | 775
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 54 | 75
Gross unrealized losses | (2) | (1)
Total available-for-sale, fair value | 834 | 849
US States And Political Subdivisions [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 140 | 162
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 27 | 32
Gross unrealized losses | 0 | 0
Total available-for-sale, fair value | 167 | 194
Foreign Governments [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 13 | 11
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 1 | 1
Gross unrealized losses | 0 | 0
Total available-for-sale, fair value | 14 | 12
Corporate Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 905 | 827
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 53 | 64
Gross unrealized losses | (5) | (1)
Total available-for-sale, fair value | 953 | 890
Residential Mortgage-Backed Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 190 | 305
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 3 | 8
Gross unrealized losses | (1) | (1)
Total available-for-sale, fair value | 192 | 312
Residential Mortgage-Backed Non-Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 80 | 22
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 12 | 3
Gross unrealized losses | 0 | 0
Total available-for-sale, fair value | 92 | 25
Commercial Mortgage-Backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 10 | 17
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 1
Gross unrealized losses | 0 | 0
Total available-for-sale, fair value | 10 | 18
Collateralized Debt Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 101 | 120
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | 0 | (2)
Total available-for-sale, fair value | 101 | 118
Other Asset-Backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Total available-for-sale, amortized cost | 95 | 121
Allowance for Credit Losess | 0 | 0
Gross unrealized gains | 0 | 0
Gross unrealized losses | (1) | 0
Total available-for-sale, fair value | $ 94 | $ 121

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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 http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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