Investments (Net Realized Gains (Losses) From Sales Of Available-For-Sale Securities) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Investments [Abstract]
Proceeds from sales	$ 339	$ 73	$ 859	$ 469
Available For Sale Securities Realized Gain Loss [Abstract]
Gross realized gains	2	1	3	7
Gross realized losses	$ (17)	$ 0	$ (42)	$ (8)

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Amount of realized gain 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
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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-Publisher FASB
-Name Accounting Standards Codification
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