Investments Investments (Schedule Of Amortized Cost and Fair Value of Available-for-sale Securities and Related OTTI Recognized in AOCI) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	$ 80,959	$ 82,580
Debt Securities, Available-for-sale, Allowance for Credit Loss	(176)	0
Available for Sale, Gross Unrealized Appreciation	2,767	3,074
Available for Sale, Gross Unrealized Depreciation	(2,020)	(166)
Available for sale, Fair Value	81,530	85,488
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		(30)
U.S. Treasury and agency
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	2,773	3,188
Debt Securities, Available-for-sale, Allowance for Credit Loss	0
Available for Sale, Gross Unrealized Appreciation	240	96
Available for Sale, Gross Unrealized Depreciation	0	(1)
Available for sale, Fair Value	3,013	3,283
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0
Foreign
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	22,615	22,670
Debt Securities, Available-for-sale, Allowance for Credit Loss	(44)
Available for Sale, Gross Unrealized Appreciation	850	1,099
Available for Sale, Gross Unrealized Depreciation	(577)	(62)
Available for sale, Fair Value	22,844	23,707
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		(25)
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	31,530	30,689
Debt Securities, Available-for-sale, Allowance for Credit Loss	(132)
Available for Sale, Gross Unrealized Appreciation	644	1,180
Available for Sale, Gross Unrealized Depreciation	(1,374)	(78)
Available for sale, Fair Value	30,668	31,791
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		(5)
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	17,073	18,712
Debt Securities, Available-for-sale, Allowance for Credit Loss	0
Available for Sale, Gross Unrealized Appreciation	864	494
Available for Sale, Gross Unrealized Depreciation	(52)	(14)
Available for sale, Fair Value	17,885	19,192
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		0
States, municipalities, and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	6,968	7,321
Debt Securities, Available-for-sale, Allowance for Credit Loss	0
Available for Sale, Gross Unrealized Appreciation	169	205
Available for Sale, Gross Unrealized Depreciation	(17)	(11)
Available for sale, Fair Value	$ 7,120	7,515
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities		$ 0

Accumulated other comprehensive loss related to portion of other than temporary impairment (OTTI) due to factors other than credit losses on debt securities categorized as available-for-sale that an entity does not intend to sell and which it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis of the debt security. The amount represented by this item is net of tax, as applicable.

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