Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Taxes Tables

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The effective tax rate of our provision (benefit) for income taxes differs from the Federal statutory rate as follows:

	Year Ended December 31,
	2020	2019
Statutory rate	21.0%	21.0%
Net operating loss expiration	(47.5)%	(14.7)%
Tax credits	2.2%	2.8%
Change in valuation allowance	24.3%	(9.1)%
Total	0.0%	0.0%

Schedule of Tax Effects of Temporary Differences that Give Rise to Significant Portions of Deferred Tax Assets and Liabilities

Deferred tax assets are summarized as follows (in thousands):

		December 31,
		2020		2019
Deferred tax assets
Reserves	$	647	$	610
Net operating loss carryforwards		83,289		85,282
R&D credit carryforwards		8,836		9,047
Depreciation/amortization deferred		15,862		16,978
Other		5,773		5,808
Net deferred taxes before valuation allowance		114,407		117,725
Less: Valuation allowance		(114,407)		(117,725)
Deferred tax assets	$	-	$	-