Investments - Schedule of Residential Mortgage Loan Investment (Details) $ in Millions	Sep. 30, 2020 USD ($)
Total Mortgage Loans
Unpaid Principal Balance	$ 1,096
% of Total	100.00%
California
Unpaid Principal Balance	$ 189
% of Total	17.00%
Florida
Unpaid Principal Balance	$ 186
% of Total	17.00%
New Jersey
Unpaid Principal Balance	$ 100
% of Total	9.00%
All Other States
Unpaid Principal Balance	$ 621
% of Total	57.00%