Investments - Debt Instruments At Fair Value (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, at fair value	$ 14,096	$ 15,558
Corporate debt securities
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, at fair value	9,828	9,793
Securities backed by real estate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, at fair value	1,316	2,280
Money market instruments
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, at fair value	1,002	1,396
Other
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, at fair value	$ 1,950	$ 2,089