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Investments (Schedule Of Amortized Cost and Fair Value of Available-for-sale Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 88,516		$ 90,493
Debt Securities, Available-for-sale, Allowance for Credit Loss	(78)	$ (27)	(14)	$ (11)	$ (15)	$ (20)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	260		3,220
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(6,629)		(591)
Available for sale, Fair Value	82,069		93,108
U.S. Treasury / Agency
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	2,248		2,111
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	9		109
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(80)		(6)
Available for sale, Fair Value	2,177		2,214
Non-U.S.
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	24,646		25,156
Debt Securities, Available-for-sale, Allowance for Credit Loss	(32)		(8)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	164		953
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(1,961)		(272)
Available for sale, Fair Value	22,817		25,829
Corporate and asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	38,166		37,844
Debt Securities, Available-for-sale, Allowance for Credit Loss	(45)		(6)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	59		1,410
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(3,133)		(185)
Available for sale, Fair Value	35,047		39,063
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	18,654		20,080
Debt Securities, Available-for-sale, Allowance for Credit Loss	(1)		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	10		532
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(1,328)		(123)
Available for sale, Fair Value	17,335		20,489
Municipal
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	4,802		5,302
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	18		216
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(127)		(5)
Available for sale, Fair Value	$ 4,693		$ 5,513