Investments (Schedule Of Amortized Cost and Fair Value of Available-for-Sale Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 127,301	$ 124,726
Debt Securities, Available-for-sale, Allowance for Credit Loss	(50)	(52)	$ (63)	$ (70)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,020	1,954
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(4,838)	(3,948)
Available for sale, Fair Value	123,433	122,680
U.S. and local government securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	3,915	3,908
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	17	27
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(235)	(221)
Available for sale, Fair Value	3,697	3,714
Non-U.S.
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	41,543	40,479
Debt Securities, Available-for-sale, Allowance for Credit Loss	(12)	(10)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	396	795
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(1,345)	(908)
Available for sale, Fair Value	40,582	40,356
Corporate and asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	49,466	48,806
Debt Securities, Available-for-sale, Allowance for Credit Loss	(38)	(42)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	367	734
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(1,963)	(1,612)
Available for sale, Fair Value	47,832	47,886
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	32,377	31,533
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	240	398
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before tax	(1,295)	(1,207)
Available for sale, Fair Value	$ 31,322	$ 30,724

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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