Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Federal tax benefit related to deferred tax liability	$ 0
State provision for income taxes	0	$ 0
(Decrease) increase in valuation allowance	3,100,000	(10,900,000)
Valuation allowance decrease due to Section 382 limited NOLs and credits		25,249,000
Valuation allowance offset amount		13,200,000
Foreign translation adjustments		$ 1,100,000
Increase in shareholders ownership interest, percentage		5.00%
Change in ownership interest, percentage points		0.50%
Change in ownership interest period		3 years
Research and orphan drug tax credit carry forwards	5,966,000	$ 4,351,000
Net operating loss carryforwards	38,969,000	36,298,000
Foreign net operating loss carryforwards	81,800,000	71,800,000
State net operating loss carryforwards	3,500,000	3,500,000
Unrecognized tax benefits	0	0
Interest and penalties related to income taxes	0	0
Internal Revenue Service ("IRS") [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		47,400,000
Research and orphan drug tax credit carry forwards		15,300,000
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	98,600,000	96,000,000.0
Research and orphan drug tax credit carry forwards	5,200,000	3,600,000
Net operating loss carryforwards	$ 52,400,000	50,600,000
Tax credit carry forwards expiration beginning year	2039
Operating loss carry forwards expiration beginning Year	2037
Operating loss carry forwards with expiration date	$ 5,200,000
Operating loss carry forwards with no expiration date	$ 93,400,000
Federal [Member] | Internal Revenue Service ("IRS") [Member]
Operating Loss Carryforwards [Line Items]
Open tax year	2018
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carry forwards expiration beginning year	2034
Operating loss carry forwards expiration beginning Year	2038
State research and development tax credit carryforwards	$ 500,000	$ 600,000
State of Texas [Member] | Internal Revenue Service ("IRS") [Member]
Operating Loss Carryforwards [Line Items]
Open tax year	2017
Foreign Tax Authorities [Member] | Internal Revenue Service ("IRS") [Member]
Operating Loss Carryforwards [Line Items]
Open tax year	2018