Investments (Schedule Of Fixed Maturities By Contractual Maturity) (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Available for sale, Due in 1 year or less, Fair Value & Net Carrying Value	$ 4,568	$ 4,760
Available for sale, Due after 1 year through 5 years, Fair Value & Net Carrying Value	25,747	26,227
Available for sale, Due after 5 years through 10 years, Fair Value & Net Carrying Value	28,117	27,232
Available for sale, Due after 10 years, Fair Value & Net Carrying Value	14,290	14,010
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value & Net Carrying Value	72,722	72,229
Available for sale, Mortgage backed securities, Fair Value & Net Carrying Value	19,963	18,470
Available for sale, Fair Value	92,685	90,699
Debt securities, Held-to-maturity, maturity, allocated and single maturity date, within one year, net carrying value	947	1,231
Held to maturity, Due in 1 year or less, Fair Value	954	1,240
Held-to-maturity, after one through five years, net carrying value	3,666	3,592
Held to maturity, Due after 1 year through 5, Fair Value	3,792	3,760
Held-to-maturity, after 5 through 10 years, net carrying value	2,498	3,029
Held to maturity, Due after 5 years through 10 years, Fair Value	2,627	3,228
Held-to-maturity, after 10 years, net carrying value	1,634	1,802
Held to maturity, Due after 10 years, Fair Value	1,878	2,136
Debt securities, Held-to-maturity, maturity, allocated and single maturity date, net carrying value	8,745	9,654
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Fair Value	9,251	10,364
Held-to-maturity, MBS, net carrying value	1,770	1,999
Held to maturity, Mortgage backed securities, Fair Value	1,868	2,146
Debt securities, held to maturity, net carrying value	10,515	11,653
Held to maturity, Fair Value	$ 11,119	$ 12,510