Investments (Schedule Of Amortized Cost And Fair Value Of HTM Fixed Maturities And Related OTTI Recognized In Accumulated Other Comprehensive Income) (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 9,852	$ 10,153
Debt Securities, Held-to-maturity, Allowance for Credit Loss	(34)	(35)	$ (43)	$ (44)
Debt securities, held to maturity, net carrying value	9,818	10,118
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	119	533
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(49)	(4)
Held to maturity, at Fair Value	9,888	10,647
U.S. Treasury / Agency
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,180	1,213
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt securities, held to maturity, net carrying value	1,180	1,213
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	12	34
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(18)	(3)
Held to maturity, at Fair Value	1,174	1,244
Non-U.S.
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,185	1,201
Debt Securities, Held-to-maturity, Allowance for Credit Loss	(5)	(5)
Debt securities, held to maturity, net carrying value	1,180	1,196
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	19	66
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(8)	0
Held to maturity, at Fair Value	1,191	1,262
Corporate and asset-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,913	2,032
Debt Securities, Held-to-maturity, Allowance for Credit Loss	(28)	(28)
Debt securities, held to maturity, net carrying value	1,885	2,004
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	56	197
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(6)	0
Held to maturity, at Fair Value	1,935	2,201
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,689	1,731
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	(1)
Debt securities, held to maturity, net carrying value	1,689	1,730
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	8	74
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(13)	(1)
Held to maturity, at Fair Value	1,684	1,803
Municipal
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	3,885	3,976
Debt Securities, Held-to-maturity, Allowance for Credit Loss	(1)	(1)
Debt securities, held to maturity, net carrying value	3,884	3,975
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	24	162
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(4)	0
Held to maturity, at Fair Value	$ 3,904	$ 4,137