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, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	$ 79,624	$ 79,323
Available-for-sale,Gross Unrealized Gain	1,480	690
Available-for-sale, Gross Unrealized Depreciation	(441)	(1,543)
Available for sale, Fair Value	80,663	78,470
Available for sale, OTTI recognized in AOCI	(6)	(7)
U.S. Treasury and agency
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	3,760	4,158
Available-for-sale,Gross Unrealized Gain	50	30
Available-for-sale, Gross Unrealized Depreciation	(19)	(43)
Available for sale, Fair Value	3,791	4,145
Available for sale, OTTI recognized in AOCI	0	0
Foreign
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	21,796	21,370
Available-for-sale,Gross Unrealized Gain	658	395
Available-for-sale, Gross Unrealized Depreciation	(112)	(349)
Available for sale, Fair Value	22,342	21,416
Available for sale, OTTI recognized in AOCI	0	0
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	27,519	27,183
Available-for-sale,Gross Unrealized Gain	476	150
Available-for-sale, Gross Unrealized Depreciation	(170)	(750)
Available for sale, Fair Value	27,825	26,583
Available for sale, OTTI recognized in AOCI	(5)	(6)
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	16,369	15,758
Available-for-sale,Gross Unrealized Gain	173	66
Available-for-sale, Gross Unrealized Depreciation	(112)	(284)
Available for sale, Fair Value	16,430	15,540
Available for sale, OTTI recognized in AOCI	(1)	(1)
States, municipalities, and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Available for sale, at amortized cost	10,180	10,854
Available-for-sale,Gross Unrealized Gain	123	49
Available-for-sale, Gross Unrealized Depreciation	(28)	(117)
Available for sale, Fair Value	10,275	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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