Income Taxes - Components of Net Accumulated Deferred Income Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets (liabilities):
Stock-based compensation	$ 1,065	$ 1,305
Depreciation and amortization	(1,111)	(825)
Section 181 qualified production expense	(3,960)	(4,668)
Net operating loss carryforward	20,791	21,212
Charitable carryforward	118	156
Other	417	542
Tax credits	276	276
Valuation allowance	(17,853)	(18,204)
Total deferred tax liabilities, net of valuation allowance	$ (257)	$ (206)