Investments (Credit quality indicator) (Details) - Mortgage loans $ in Millions	Sep. 30, 2021 USD ($)
Debt Securities, Available-for-sale [Line Items]
2021	$ 63
2020	161
2019	282
2018	86
2017	169
Prior	296
Total	1,057
DSCR ≥1.6x | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	8
2020	75
2019	16
2018	37
2017	116
Prior	203
Total	455
DSCR ≥1.6x | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	38
2019	15
2018	18
2017	0
Prior	1
Total	72
DSCR ≥1.6x | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	17
2020	0
2019	14
2018	7
2017	0
Prior	23
Total	61
DSCR 1.2x - 1.6x | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	13
2020	15
2019	95
2018	0
2017	5
Prior	58
Total	186
DSCR 1.2x - 1.6x | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	25
2020	0
2019	0
2018	24
2017	10
Prior	4
Total	63
DSCR 1.2x - 1.6x | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	24
2019	9
2018	0
2017	8
Prior	0
Total	41
DSCR ≤1.2 | LTV less than 55%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	35
2018	0
2017	30
Prior	0
Total	65
DSCR ≤1.2 | LTV 55% to 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	42
2018	0
2017	0
Prior	0
Total	42
DSCR ≤1.2 | LTV greater than 65%
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	9
2019	56
2018	0
2017	0
Prior	7
Total	$ 72