Investments (Aggregate Fair Value And Gross Unrealized Loss By Length Of Time Security Has Continuously Been In Unrealized Loss Position) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 49,564	$ 25,041
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2,244)	(465)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	6,129	2,159
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(598)	(104)
Debt Securities, Available-for-sale, Unrealized Loss Position	55,693	27,200
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(2,842)	(569)
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	946	363
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(31)	(3)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	98	70
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(9)	(3)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,044	433
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(40)	(6)
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	12,654	6,917
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(608)	(196)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,385	1,093
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(222)	(62)
Debt Securities, Available-for-sale, Unrealized Loss Position	15,039	8,010
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(830)	(258)
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	21,082	9,449
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(899)	(145)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,041	806
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(216)	(32)
Debt Securities, Available-for-sale, Unrealized Loss Position	23,123	10,255
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(1,115)	(177)
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	13,657	8,086
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(646)	(116)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,589	190
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(150)	(7)
Debt Securities, Available-for-sale, Unrealized Loss Position	15,246	8,276
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	(796)	(123)
Municipal
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,225	226
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(60)	(5)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	16	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1)	0
Debt Securities, Available-for-sale, Unrealized Loss Position	1,241	226
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (61)	$ (5)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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