Insurance Premiums (Narrative) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Insurance Premiums [Line Items]
Premiums receivable		$ 178	$ 216	$ 249
Weighted average risk-free rate		2.80%	2.70%
Weighted average expected collection term of the premiums receivable, years		9 years 1 month 2 days	8 years 9 months
Reinsurance premiums payable	[1]	$ 48
Premiums [Member]
Insurance Premiums [Line Items]
Premiums receivable		5	$ 5
Reinsurance premiums payable		$ 5	$ 15

[1] Total reinsurance recoverable/(payable) is primarily related to recoverables on unpaid losses net of (payables) on salvage received.