Income Taxes (Narrative) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Impairment of in-process research and development	$ 0
Unrecognized tax benefits	0	$ 0
Interest and penalties pertaining to income tax examination recognized	$ 0
U.S. federal statutory income tax rate	21.00%	21.00%
Current tax expense on US and Foreign pre tax losses	$ 0	$ 0
Domestic Tax Authority [Member]
Net operating loss carryforwards ("NOLs")	145,000,000
State and Local Jurisdiction [Member]
Net operating loss carryforwards ("NOLs")	$ 116,000,000