Investments - Amortized Cost Basis of Mortgage Loans for Each Credit Quality Indicator by Year of Origination (Details) - Commercial mortgage-backed $ in Millions	Sep. 30, 2022 USD ($)
Credit Quality Information [Abstract]
2022	$ 129
2021	94
2020	150
2019	208
2018	64
Prior	332
Total	977
DSCR Greater than or Equal to 1.6x, LTV Less than 55%
Credit Quality Information [Abstract]
2022	9
2021	13
2020	112
2019	29
2018	54
Prior	275
Total	492
DSCR Greater than or Equal to 1.6x, LTV 55% to 65%
Credit Quality Information [Abstract]
2022
2021
2020
2019
2018
Prior
Total	0
DSCR Greater than or Equal to 1.6x, LTV Greater than 65%
Credit Quality Information [Abstract]
2022	18
2021	11
2020
2019
2018
Prior
Total	29
DSCR Between 1.2 to 1.6x, LTV Less than 55%
Credit Quality Information [Abstract]
2022	5
2021	49
2020	18
2019	56
2018	10
Prior	42
Total	180
DSCR Between 1.2 to 1.6x, LTV 55% to 65%
Credit Quality Information [Abstract]
2022	87
2021
2020	20
2019
2018
Prior	8
Total	115
DSCR Between 1.2 to 1.6x, LTV Greater than 65%
Credit Quality Information [Abstract]
2022
2021
2020
2019
2018
Prior
Total	0
DSCR Less than or Equal to 1.2x, LTV Less than 55%
Credit Quality Information [Abstract]
2022
2021
2020
2019	57
2018
Prior
Total	57
DSCR Three, LTV 55 to 65%
Credit Quality Information [Abstract]
2022
2021	21
2020
2019	44
2018
Prior
Total	65
DSCR Less than or Equal to 1.2x, LTV Greater than 65%
Credit Quality Information [Abstract]
2022	10
2021
2020
2019	22
2018
Prior	7
Total	$ 39