Investments (Securities Held In Unrealized Loss Position And Insured By Financial Guarantor) (Detail) - Financial Guarantee [Member] $ in Millions	Jun. 30, 2023 USD ($)
Schedule Of Investments [Line Items]
Fair value	$ 109
Unrealized loss	(30)
Insurance loss reserve	29
Mortgage-backed [Member]
Schedule Of Investments [Line Items]
Fair value	25
Unrealized loss	(5)
Insurance loss reserve	29
Corporate Obligations [Member]
Schedule Of Investments [Line Items]
Fair value	84
Unrealized loss	(25)
Insurance loss reserve	$ 0