Note 4 - Income Taxes - Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net operating loss	$ 105,233	$ 85,214	$ 73,436
Stock option expense	23,643	18,709	12,169
Property and equipment	(35,756)	(20,753)	(14,957)
Other	5,536	5,920	2,845
Less: Valuation allowance	(98,656)	(89,090)	(73,493)
Net deferred income tax assets	$ 0	$ 0	$ 0

Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

+ References

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-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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-SubTopic 10
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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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