Investments (Schedule Of Available-For-Sale Securities Whose Value Is Below Amortized Cost) (Details) $ in Millions	Dec. 31, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Schedule of Available-for-sale Securities [Line Items]
Fair Value - Nine months or greater, but less than twelve months	$ 16,570	$ 4,552
Fair Value - Twelve months or greater	1,781	1,045
Fair Value - Total	18,351	5,597
Gross Unrealized Losses - Nine months or greater, but less than twelve months	308	110
Gross Unrealized Losses - Twelve months or greater	119	74
Gross Unrealized Losses - Total	$ 427	$ 184
Number of Securities - Total | security	2,577	782
Fair Value Decline, Greater Than 20% [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value - Less than six months	$ 12	$ 63
Fair Value - Six months or greater, but less than nine months		2
Fair Value - Nine months or greater, but less than twelve months		22
Fair Value - Twelve months or greater	58	30
Fair Value - Total	70	117
Gross Unrealized Losses - Less than six months	3	23
Gross Unrealized Losses - Six months or greater, but less than nine months		1
Gross Unrealized Losses - Nine months or greater, but less than twelve months		6
Gross Unrealized Losses - Twelve months or greater	8	11
Gross Unrealized Losses - Total	$ 11	$ 41
Number of Securities - Less than six months | security	6	14
Number of Securities - Six months or greater, but less than nine months | security		4
Number of Securities - Nine months or greater, but less than twelve months | security		13
Number of Securities - Twelve months or greater | security	24	20
Number of Securities - Total | security	30	51