Income Taxes - Significant Components of Company's Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Non-current deferred tax assets:
Federal and state net operating loss carryforwards	$ 35,091	$ 28,532
Research and other credits	2,349	2,037
Reserves and accruals	77	52
Assets held for sale		15
Fixed assets	71	67
Capital loss carryover	1,115	425
Stock based compensation	85	70
Lease liability	131
Other deferred tax assets	196	542
Gross non-current deferred tax assets	39,115	31,740
Intangible assets	(4,623)	(4,062)
Right-of-use assets	(118)
Total non-current deferred tax liabilities	(4,741)	(4,062)
Total deferred tax assets	34,374	27,678
Valuation allowance	$ (34,374)	$ (27,678)