Investments (Schedule Of Amortized Cost and Fair Value of Available-for-Sale Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 104,224		$ 93,355
Debt Securities, Available-for-sale, Allowance for Credit Loss	(193)	$ (168)	(169)	$ (78)	$ (27)	$ (14)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	382		174
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(7,624)		(8,140)
Available for sale, Fair Value	96,789		85,220
U.S. Treasury / Agency
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	3,942		2,792
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	6		5
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(204)		(171)
Available for sale, Fair Value	3,744		2,626
Non-U.S.
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	31,513		28,064
Debt Securities, Available-for-sale, Allowance for Credit Loss	(64)		(59)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	267		108
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(2,014)		(2,205)
Available for sale, Fair Value	29,702		25,908
Corporate and asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	43,348		40,547
Debt Securities, Available-for-sale, Allowance for Credit Loss	(127)		(107)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	90		49
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(3,134)		(3,534)
Available for sale, Fair Value	40,177		36,955
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	20,032		17,871
Debt Securities, Available-for-sale, Allowance for Credit Loss	(2)		(3)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	10		4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(2,068)		(2,021)
Available for sale, Fair Value	17,972		15,851
Municipal
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,389		4,081
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	9		8
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(204)		(209)
Available for sale, Fair Value	$ 5,194		$ 3,880