Investments (Schedule Of Available-For-Sale Securities Whose Value Is Below Amortized Cost) (Details) - Fair Value Decline, Greater Than 20% [Member] $ in Millions	Mar. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Schedule of Available-for-sale Securities [Line Items]
Fair Value - Less than six months	$ 2,458	$ 11,351
Fair Value - Six months or greater, but less than nine months	4,420	4,411
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	4,350	447
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	425	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	11,653	16,211
Gross Unrealized Losses - Less than six months	780	3,659
Gross Unrealized Losses - Six months or greater, but less than nine months	1,503	2,226
Less Than or Equal to Twelve Months	1,968	302
Greater Than Twelve Months	260	1
Continuous Unrealized Loss Position, Total	$ 4,511	$ 6,188
Number of Securities - Less than six months | security	436	1,500
Number of Securities - Six months or greater, but less than nine months | security	728	650
Number of Securities - Nine months or greater, but less than twelve months | security	638	74
Number of Securities - Twelve months or greater | security	86	15
Number of Securities - Total | security	1,888	2,239