Income Taxes - Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
59 (e) expenditures and amortization	$ 21,833	$ 6,222
Net operating loss carryforwards	13,546	14,011
Federal R&D and orphan drug credits	11,992	5,107
Stock based compensation	8,806	6,459
License fee	4,691	3,224
Other	1,468	1,024
Gross deferred tax assets	62,336	36,047
Valuation allowance	(61,847)	(35,513)
Total deferred tax assets	489	534
Deferred tax liabilities:
Lease Asset	19	114
Other	82	73
Total deferred tax liabilities	101	187
Total net deferred tax assets	$ 388	$ 347