Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Available For Sale Securities Debt Maturities Amortized Cost
Due in one year or less	$ 1,417
Due after one year through five years	8,267
Due after five year through ten years	10,389
Due after ten years	21,824
Asset and mortgage-backed securities	6,764
Total	48,661	$ 46,753
Available For Sale Securities Debt Maturities Fair Value
Due in one year or less	1,416
Due after one year through five years	8,751
Due after five year through ten years	11,456
Due after ten years	26,150
Asset and mortgage-backed securities	6,879
Total	$ 54,652	$ 51,121

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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