Commercial Mortgage Loans By Year of Origination and Credit Quality Indicator (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	$ 7,088	$ 6,856
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	7,088	6,856
0% - 50%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	2,388	2,480
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	2,388
51% - 60%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	1,506	1,539
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	1,506
61% - 75%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	3,194	2,815
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	3,194
76% - 100%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0	0
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
Greater than 100%
Disclosure Of Commercial Mortgage Loans By Year Of Origination And Credit Quality Indicator [Line Items]
Commercial mortgage loans, amortized cost	0	22
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
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	183	223
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	526	559
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	903	791
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	3,242	2,958
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	2,234	$ 2,325
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	565
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	2
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	31
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	532
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	0
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	13
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	138
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	368
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	46
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	937
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	25
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	37
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	875
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	0
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	0
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	2
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	117
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	716
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	102
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	519
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	72
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	33
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	414
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	0
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	10
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	69
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	31
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	217
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	192
2019 | 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	722
2019 | 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	62
2019 | 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	178
2019 | 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	482
2019 | 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
2019 | 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
2019 | 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	19
2019 | 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	72
2019 | 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	166
2019 | 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	268
2019 | 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	197
2018 | 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	852
2018 | 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	165
2018 | 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	293
2018 | 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	394
2018 | 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
2018 | 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
2018 | 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	40
2018 | 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	74
2018 | 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	133
2018 | 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	425
2018 | 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	180
2017 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	3,493
2017 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	2,062
2017 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	934
2017 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	497
2017 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	0
2017 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	0
2017 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	114
2017 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	296
2017 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	318
2017 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	1,248
2017 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	$ 1,517