Commitments and Contingencies (Lease Disclosures) (Detail) $ in Millions	Dec. 31, 2023 USD ($)
Operating lease right of use asset	$ 15
Operating lease liability	$ 15
Operating lease weighted average remaining lease term	6 years 8 months 12 days
Operating lease weighted average discount rate percent	7.50%
Operating leases future minimum payments due	$ 20
Operating lease right of use asset	Other Assets
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities