Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets:
Accrued liabilities	$ 1,396	$ 916
Stock-based compensation	3,666	2,623
Net operating loss carryovers	75,853	76,098
Tax credit carryovers	13,055	13,206
Other	1,537	1,053
Total deferred tax assets	95,507	93,896
Less valuation allowance	(93,611)	(90,959)
Deferred tax assets, net of valuation allowance	1,896	2,937
Deferred Tax Liabilities:
Fixed assets	(570)	(2,352)
Intangible assets	(298)	(152)
Total deferred tax liabilities	(868)	(2,504)
Net deferred tax assets (liability)	$ 1,028	$ 433