Investments, Amortized Cost Basis of Mortgage Loans for Each Credit Quality Indicator by Year of Origination (Details) - Mortgage Loans [Member] $ in Millions	Jun. 30, 2021 USD ($)	[1]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2021	$ 15
2020	161
2019	283
2018	92
2017	170
Prior	311
Total	1,032
DSCR Greater than or Equal to 1.6x, LTV Less than 55% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2020	89
2019	33
2018	50
2017	113
Prior	183
Total	468
DSCR Greater than or Equal to 1.6x, LTV 55% to 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	19
2017	9
Prior	4
Total	32
DSCR Greater than or Equal to 1.6x, LTV Greater than 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2021	5
2019	6
Prior	24
Total	35
DSCR Between 1.2 to 1.6x, LTV Less than 55% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	16
2017	5
Prior	71
Total	92
DSCR Between 1.2 to 1.6x, LTV 55% to 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2021	10
2020	38
2019	39
2018	42
2017	27
Total	156
DSCR Between 1.2 to 1.6x, LTV Greater than 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2020	34
2019	44
2017	8
Prior	12
Total	98
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
Prior	10
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	47
Total	47
DSCR Less than or Equal to 1.2x, LTV Greater than 65% [Member]
Mortgage Loans Amortized Cost Basis by Origination Year [Abstract]
2019	29
Prior	7
Total	$ 36

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