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	$ 2,411	$ 10,895
Fair Value - Six months or greater, but less than nine months	4,356	4,256
Fair Value - Nine months or greater, but less than twelve months	4,300	362
Fair Value - Twelve months or greater	374	2
Fair Value - Total	11,441	15,515
Gross Unrealized Losses - Less than six months	690	3,514
Gross Unrealized Losses - Six months or greater, but less than nine months	1,429	2,150
Gross Unrealized Losses - Nine months or greater, but less than twelve months	1,924	243
Gross Unrealized Losses - Twelve months or greater	226
Gross Unrealized Losses - Total	$ 4,269	$ 5,907
Number of Securities - Less than six months | security	359	1,489
Number of Securities - Six months or greater, but less than nine months | security	691	640
Number of Securities - Nine months or greater, but less than twelve months | security	627	73
Number of Securities - Twelve months or greater | security	85	15
Number of Securities - Total | security	1,762	2,217