Investments, Amortized Cost Basis of Mortgage Loans for Each Credit Quality Indicator by Year of Origination (Details) - Mortgage Loans [Member] $ in Millions	Dec. 31, 2020 USD ($)	[1]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2020	$ 161
2019	284
2018	103
2017	215
2016	85
Prior	246
Total	1,094
DSCR Greater than or Equal to 1.6x, LTV Less than 55% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2020	75
2019	33
2018	36
2017	115
2016	33
Prior	156
Total	448
DSCR Greater than or Equal to 1.6x, LTV 55% to 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2020	14
2019	20
2018	14
2017	15
2016	11
Total	74
DSCR Greater than or Equal to 1.6x, LTV Greater than 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	5
2016	25
Total	30
DSCR Between 1.2 to 1.6x, LTV Less than 55% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	17
2017	5
2016	9
Prior	68
Total	99
DSCR Between 1.2 to 1.6x, LTV 55% to 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2020	20
2019	29
2018	53
2017	27
Total	129
DSCR Between 1.2 to 1.6x, LTV Greater than 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2020	52
2019	54
2017	8
Prior	12
Total	126
DSCR Less than or Equal to 1.2x, LTV Less than 55% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	50
2017	8
2016	7
Prior	3
Total	68
DSCR Less than or Equal to 1.2x, LTV 55% to 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	48
Total	48
DSCR Less than or Equal to 1.2x, LTV Greater than 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	28
2017	37
Prior	7
Total	$ 72

[1] The values in the table above reflect DSCR on a standardized amortization period and LTV based on the most recent appraised values trended forward using changes in a commercial real estate price index.