Investments (Schedule Of Available-For-Sale Securities Whose Value Is Below Amortized Cost) (Details) $ in Millions	Sep. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 24,976	$ 71,770
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	60,062	11,352
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	85,038	83,122
Less Than or Equal to Twelve Months	1,718	10,425
Greater Than Twelve Months	13,097	2,593
Continuous Unrealized Loss Position, Total	$ 14,815	$ 13,018
Number of Securities - Total | security	8,590	8,175
Fair Value Decline, Greater Than 20% [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value - Less than six months	$ 10,439	$ 11,351
Fair Value - Six months or greater, but less than nine months	802	4,411
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	183	447
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	5,386	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	16,810	16,211
Gross Unrealized Losses - Less than six months	3,443	3,659
Gross Unrealized Losses - Six months or greater, but less than nine months	439	2,226
Less Than or Equal to Twelve Months	85	302
Greater Than Twelve Months	4,036	1
Continuous Unrealized Loss Position, Total	$ 8,003	$ 6,188
Number of Securities - Less than six months | security	1,362	1,500
Number of Securities - Six months or greater, but less than nine months | security	176	650
Number of Securities - Nine months or greater, but less than twelve months | security	25	74
Number of Securities - Twelve months or greater | security	1,057	15
Number of Securities - Total | security	2,620	2,239