Investments (Aggregate Fair Value And Gross Unrealized Loss By Length Of Time Security Has Continuously Been In Unrealized Loss Position) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 17,393	$ 8,569
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(226)	(176)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	52,606	53,950
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(4,895)	(4,129)
Debt Securities, Available-for-sale, Unrealized Loss Position	69,999	62,519
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(5,121)	(4,305)
U.S. Treasury / Agency
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	509	463
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(4)	(9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,050	2,504
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(164)	(135)
Debt Securities, Available-for-sale, Unrealized Loss Position	2,559	2,967
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(168)	(144)
Non-U.S.
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	5,388	2,464
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(94)	(43)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	15,668	15,971
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,095)	(957)
Debt Securities, Available-for-sale, Unrealized Loss Position	21,056	18,435
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,189)	(1,000)
Corporate and asset-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	5,903	2,866
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(68)	(51)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	19,214	20,334
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,476)	(1,194)
Debt Securities, Available-for-sale, Unrealized Loss Position	25,117	23,200
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,544)	(1,245)
Mortgage-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	5,439	1,659
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(57)	(58)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	14,205	13,831
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,999)	(1,706)
Debt Securities, Available-for-sale, Unrealized Loss Position	19,644	15,490
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(2,056)	(1,764)
Municipal
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	154	1,117
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(3)	(15)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,469	1,310
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(161)	(137)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,623	2,427
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (164)	$ (152)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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