Investments (Aggregate Fair Value And Gross Unrealized Loss By Length Of Time Security Has Continuously Been In Unrealized Loss Position) (Details) - USD ($) $ in Millions	Dec. 31, 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	$ 27,956	$ 8,569
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(518)	(176)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	39,789	53,950
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(4,230)	(4,129)
Debt Securities, Available-for-sale, Unrealized Loss Position	67,745	62,519
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(4,748)	(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	418	463
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(7)	(9)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,477	2,504
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(153)	(135)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,895	2,967
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(160)	(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	6,630	2,464
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(138)	(43)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	12,023	15,971
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(874)	(957)
Debt Securities, Available-for-sale, Unrealized Loss Position	18,653	18,435
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,012)	(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	10,069	2,866
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(194)	(51)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	13,290	20,334
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,259)	(1,194)
Debt Securities, Available-for-sale, Unrealized Loss Position	23,359	23,200
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,453)	(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	10,490	1,659
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(170)	(58)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	11,987	13,831
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,794)	(1,706)
Debt Securities, Available-for-sale, Unrealized Loss Position	22,477	15,490
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,964)	(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	349	1,117
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(9)	(15)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,012	1,310
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(150)	(137)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,361	2,427
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (159)	$ (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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