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, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Schedule of Available-for-sale Securities [Line Items]
Fair Value - Less than six months	$ 529	$ 12
Fair Value - Twelve months or greater	38	58
Fair Value - Total	567	70
Gross Unrealized Losses - Less than six months	146	3
Gross Unrealized Losses - Twelve months or greater	6	8
Gross Unrealized Losses - Total	$ 152	$ 11
Number of Securities - Less than six months | security	82	6
Number of Securities - Twelve months or greater | security	21	24
Number of Securities - Total | security	103	30