Investments Investments (Details) - Contractual Maturities - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Fixed maturities, due in one year or less, amortized cost	$ 3,738
Fixed maturities, due after 1 year through 5 years, amortized cost	17,729
Fixed maturities, due after 5 years through 10 years, amortized cost	17,262
Fixed maturities, due after 10 years, amortized cost	23,360
Fixed maturities excluding mortgage-backed securities, collateralized mortgage obligations and pass-through securities, amortized cost	62,089
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities, amortized cost	3,192
Fixed maturities, amortized cost	65,281	$ 63,601
Fixed maturities, due in one year or less, fair value	3,760
Fixed maturities, due after 1 year through 5 years, fair value	18,241
Fixed maturities, due after 5 years through 10 years, fair value	18,215
Fixed maturities, due after 10 years, fair value	24,638
Fixed maturities excluding mortgage-backed securities, collateralized mortgage obligations and pass-through securities, fair value	64,854
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities, fair value	3,280
Fixed maturities, at fair value	$ 68,134	$ 63,464