Commercial Mortgage Loans By Year of Origination and Credit Quality Indicator (Detail) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	$ 6,570	$ 6,829
Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	6,570	6,829
0% - 50%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	2,351	2,368
0% - 50% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	2,351
51% - 60%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	1,293	1,393
51% - 60% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	1,293
61% - 75%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	2,584	3,018
61% - 75% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	2,584
76% - 100%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	306	50
76% - 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	306
Greater than 100%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	36	0
Greater than 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	36
Less than 1.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	281	265
1.00 - 1.25 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	432	263
1.26 - 1.50 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	1,027	1,196
1.51 - 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	2,546	2,611
Greater than 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	2,284	$ 2,494
2024 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	171
2024 | 0% - 50% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	33
2024 | 51% - 60% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	15
2024 | 61% - 75% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	123
2024 | 76% - 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2024 | Greater than 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2024 | Less than 1.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2024 | 1.00 - 1.25 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	4
2024 | 1.26 - 1.50 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	81
2024 | 1.51 - 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	54
2024 | Greater than 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	32
2023 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	268
2023 | 0% - 50% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	38
2023 | 51% - 60% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	15
2023 | 61% - 75% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	215
2023 | 76% - 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2023 | Greater than 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2023 | Less than 1.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	20
2023 | 1.00 - 1.25 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	14
2023 | 1.26 - 1.50 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	154
2023 | 1.51 - 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	49
2023 | Greater than 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	31
2022 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	914
2022 | 0% - 50% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	87
2022 | 51% - 60% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	238
2022 | 61% - 75% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	539
2022 | 76% - 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	50
2022 | Greater than 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2022 | Less than 1.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2022 | 1.00 - 1.25 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	50
2022 | 1.26 - 1.50 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	139
2022 | 1.51 - 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	459
2022 | Greater than 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	266
2021 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	888
2021 | 0% - 50% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	108
2021 | 51% - 60% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	230
2021 | 61% - 75% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	526
2021 | 76% - 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	24
2021 | Greater than 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2021 | Less than 1.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	3
2021 | 1.00 - 1.25 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	35
2021 | 1.26 - 1.50 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	40
2021 | 1.51 - 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	439
2021 | Greater than 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	371
2020 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	467
2020 | 0% - 50% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	115
2020 | 51% - 60% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	87
2020 | 61% - 75% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	213
2020 | 76% - 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	52
2020 | Greater than 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0
2020 | Less than 1.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	12
2020 | 1.00 - 1.25 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	51
2020 | 1.26 - 1.50 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	74
2020 | 1.51 - 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	154
2020 | Greater than 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	176
2019 and prior | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	3,862
2019 and prior | 0% - 50% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	1,970
2019 and prior | 51% - 60% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	708
2019 and prior | 61% - 75% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	968
2019 and prior | 76% - 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	180
2019 and prior | Greater than 100% | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	36
2019 and prior | Less than 1.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	246
2019 and prior | 1.00 - 1.25 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	278
2019 and prior | 1.26 - 1.50 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	539
2019 and prior | 1.51 - 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	1,391
2019 and prior | Greater than 2.00 | Fixed Rate Commercial Mortgage Loans
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	$ 1,408