Investments (Available-For-Sale Securities By Contractual Maturities) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Available-for-sale Securities, Debt Maturities, Amortized Cost
Amortized Cost	$ 96,217	$ 94,295
Available-for-sale Securities, Debt Maturities, Fair Value
Fair Value	102,606	105,200
Fixed Maturity AFS Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost
Due in one year or less	3,008
Due after one year through five years	14,806
Due after five years through ten years	17,319
Due after ten years	51,722
Amortized Cost	96,217	94,295
Available-for-sale Securities, Debt Maturities, Fair Value
Due in one year or less	2,980
Due after one year through five years	14,836
Due after five years through ten years	17,804
Due after ten years	57,510
Fair Value	102,606	$ 105,200
Fixed Maturity AFS Securities [Member] \| Fixed maturity AFS securities other than structured securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost
Amortized Cost	86,855
Available-for-sale Securities, Debt Maturities, Fair Value
Fair Value	93,130
Fixed Maturity AFS Securities [Member] \| Structured securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost
Amortized Cost	9,362
Available-for-sale Securities, Debt Maturities, Fair Value
Fair Value	$ 9,476

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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