Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Available For Sale Securities Debt Maturities Amortized Cost
Due in one year or less	$ 1,176
Due after one year through five years	8,125
Due after five year through ten years	9,629
Due after ten years	20,668
Asset and mortgage-backed securities	7,022
Total	46,620	$ 46,753
Available For Sale Securities Debt Maturities Fair Value
Due in one year or less	1,172
Due after one year through five years	8,184
Due after five year through ten years	9,880
Due after ten years	22,552
Asset and mortgage-backed securities	6,767
Total	$ 48,555	$ 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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