Investments (Credit quality indicator) (Details) - Mortgage loans $ in Millions	Mar. 31, 2021 USD ($)
Debt Securities, Available-for-sale [Line Items]
2021	$ 15
2020	161
2019	284
2018	103
2017	178
Prior	328
Total	1,069
DSCR ≥1.6x | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	75
2019	32
2018	36
2017	114
Prior	187
Total	444
DSCR ≥1.6x | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	14
2019	20
2018	14
2017	15
Prior	11
Total	74
DSCR ≥1.6x | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	5
2020	0
2019	5
2018	0
2017	0
Prior	24
Total	34
DSCR 1.2x - 1.6x | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	16
2018	0
2017	5
Prior	77
Total	98
DSCR 1.2x - 1.6x | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	20
2019	40
2018	53
2017	27
Prior	0
Total	140
DSCR 1.2x - 1.6x | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	10
2020	52
2019	44
2018	0
2017	9
Prior	12
Total	127
DSCR ≤1.2 | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	50
2018	0
2017	8
Prior	10
Total	68
DSCR ≤1.2 | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	48
2018	0
2017	0
Prior	0
Total	48
DSCR ≤1.2 | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	29
2018	0
2017	0
Prior	7
Total	$ 36