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, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 79,323	$ 77,835
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	690	1,528
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1,543)	(424)
Available for sale, Fair Value	78,470	78,939
Available for sale, OTTI recognized in AOCI	(7)	(6)
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	4,158	3,701
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	30	32
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(43)	(35)
Available for sale, Fair Value	4,145	3,698
Available for sale, OTTI recognized in AOCI	0	0
Foreign
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	21,370	20,514
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	395	622
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(349)	(106)
Available for sale, Fair Value	21,416	21,030
Available for sale, OTTI recognized in AOCI	0	(1)
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	27,183	23,453
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	150	638
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(750)	(95)
Available for sale, Fair Value	26,583	23,996
Available for sale, OTTI recognized in AOCI	(6)	(4)
Collateralized Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	15,758	15,279
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	66	111
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(284)	(100)
Available for sale, Fair Value	15,540	15,290
Available for sale, OTTI recognized in AOCI	(1)	(1)
States, municipalities, and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	10,854	14,888
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	49	125
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(117)	(88)
Available for sale, Fair Value	10,786	14,925
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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