Investments Investments (Schedule Of Amortized Cost and Fair Value of Available-for-sale Securities and Related OTTI Recognized in AOCI) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	$ 85,201		$ 82,580
Debt Securities, Available-for-sale, Allowance for Credit Loss	(34)	$ (69)	0
Available for Sale, Gross Unrealized Appreciation	5,050		3,074
Available for Sale, Gross Unrealized Depreciation	(365)		(166)
Available for sale, Fair Value	89,852		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 / Agency
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	2,564		3,188
Debt Securities, Available-for-sale, Allowance for Credit Loss	0
Available for Sale, Gross Unrealized Appreciation	227		96
Available for Sale, Gross Unrealized Depreciation	0		(1)
Available for sale, Fair Value	2,791		3,283
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities			0
Non-U.S.
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	23,858		22,670
Debt Securities, Available-for-sale, Allowance for Credit Loss	(9)
Available for Sale, Gross Unrealized Appreciation	1,548		1,099
Available for Sale, Gross Unrealized Depreciation	(115)		(62)
Available for sale, Fair Value	25,282		23,707
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities			(25)
Corporate and asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	33,661		30,689
Debt Securities, Available-for-sale, Allowance for Credit Loss	(25)
Available for Sale, Gross Unrealized Appreciation	1,895		1,180
Available for Sale, Gross Unrealized Depreciation	(233)		(78)
Available for sale, Fair Value	35,298		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	18,272		18,712
Debt Securities, Available-for-sale, Allowance for Credit Loss	0
Available for Sale, Gross Unrealized Appreciation	1,078		494
Available for Sale, Gross Unrealized Depreciation	(13)		(14)
Available for sale, Fair Value	19,337		19,192
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities			0
Municipal
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	6,846		7,321
Debt Securities, Available-for-sale, Allowance for Credit Loss	0
Available for Sale, Gross Unrealized Appreciation	302		205
Available for Sale, Gross Unrealized Depreciation	(4)		(11)
Available for sale, Fair Value	$ 7,144		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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