Variable Interest Entities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Mortgage loans, net of allowances	$ 17,385	$ 15,938
Investment funds	6,865	6,087
Other assets (consolidated variable interest entities: 2021 – $173 and 2020 – $1)	1,785	1,249
Investments, excluding investments in Related Party
Variable Interest Entity [Line Items]
Mortgage loans, net of allowances	16,671	15,264
Investment funds	966	803
Variable Interest Entities
Variable Interest Entity [Line Items]
Other assets (consolidated variable interest entities: 2021 – $173 and 2020 – $1)	173	1
Variable Interest Entities | Investments, excluding investments in Related Party
Variable Interest Entity [Line Items]
Mortgage loans, net of allowances	1,812	1,880
Investment funds	154	0
Variable Interest Entities | Investments, excluding investments in Related Party | Hamlet
Variable Interest Entity [Line Items]
Mortgage loans, net of allowances	1,812	$ 1,880
Variable Interest Entities | Investments, excluding investments in Related Party | Java
Variable Interest Entity [Line Items]
Investment funds	24
Other assets (consolidated variable interest entities: 2021 – $173 and 2020 – $1)	151
Variable Interest Entities | Investments, excluding investments in Related Party | A-A SPN-9
Variable Interest Entity [Line Items]
Investment funds	$ 130