Investments Investments (Schedule Of Amortized Cost and Fair Value of Available-for-sale Securities and Related OTTI Recognized in AOCI) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 82,580	$ 79,323
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,074	690
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(166)	(1,543)
Available for sale, Fair Value	85,488	78,470
Available for sale, OTTI recognized in AOCI	(30)	(7)
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	3,188	4,158
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	96	30
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1)	(43)
Available for sale, Fair Value	3,283	4,145
Available for sale, OTTI recognized in AOCI	0	0
Foreign
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	22,670	21,370
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,099	395
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(62)	(349)
Available for sale, Fair Value	23,707	21,416
Available for sale, OTTI recognized in AOCI	(25)	0
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	30,689	27,183
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,180	150
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(78)	(750)
Available for sale, Fair Value	31,791	26,583
Available for sale, OTTI recognized in AOCI	(5)	(6)
Collateralized Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	18,712	15,758
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	494	66
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(14)	(284)
Available for sale, Fair Value	19,192	15,540
Available for sale, OTTI recognized in AOCI	0	(1)
States, municipalities, and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	7,321	10,854
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	205	49
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(11)	(117)
Available for sale, Fair Value	7,515	10,786
Available for sale, OTTI recognized in AOCI	$ 0	$ 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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