Commitments and Contingencies (Lease Disclosures) (Detail) $ in Millions	Sep. 30, 2021 USD ($)
Operating lease weighted average remaining lease term	8 years 7 months 6 days
Operating lease weighted average discount rate percent	7.50%
Operating leases future minimum payments due	$ 26
Other Assets [Member]
Operating lease right of use asset	19
Other Liabilities [Member]
Operating lease liability	$ 19