Investments - Amortized Cost Basis of Mortgage Loans for Each Credit Quality Indicator by Year of Origination (Details) - Commercial mortgage-backed $ in Millions	Sep. 30, 2024 USD ($)
Credit Quality Information [Abstract]
2024	$ 43
2023	126
2022	247
2021	76
2020	134
Prior	412
Total	1,038
DSCR Greater than or Equal to 1.6x, LTV Less than 55%
Credit Quality Information [Abstract]
2024
2023	33
2022	9
2021	2
2020	97
Prior	242
Total	383
DSCR Greater than or Equal to 1.6x, LTV 55% to 65%
Credit Quality Information [Abstract]
2024
2023
2022
2021	5
2020
Prior
Total	5
DSCR Greater than or Equal to 1.6x, LTV Greater than 65%
Credit Quality Information [Abstract]
2024
2023
2022	30
2021	12
2020
Prior
Total	42
DSCR Between 1.2 to 1.6x, LTV Less than 55%
Credit Quality Information [Abstract]
2024
2023	28
2022	5
2021
2020	13
Prior	50
Total	96
DSCR Between 1.2 to 1.6x, LTV 55% to 65%
Credit Quality Information [Abstract]
2024	43
2023	20
2022	36
2021	36
2020	4
Prior	31
Total	170
DSCR Between 1.2 to 1.6x, LTV Greater than 65%
Credit Quality Information [Abstract]
2024
2023	13
2022	64
2021
2020	20
Prior
Total	97
DSCR Less than or Equal to 1.2x, LTV Less than 55%
Credit Quality Information [Abstract]
2024
2023
2022
2021
2020
Prior
Total	0
DSCR Less than or Equal to 1.2x, LTV 55 to 65%
Credit Quality Information [Abstract]
2024
2023	32
2022	75
2021
2020
Prior	41
Total	148
DSCR Less than or Equal to 1.2x, LTV Greater than 65%
Credit Quality Information [Abstract]
2024
2023
2022	28
2021	21
2020
Prior	48
Total	$ 97

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- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
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