Note 7 - Income Taxes (Details Textual) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Deferred Tax Assets, Net	$ 449.7	$ 439.7
Deferred Tax Assets, Valuation Allowance	451.9	$ 441.9
SPO [Member]
Deferred Tax Assets, Net	65.7
Deferred Tax Assets, Valuation Allowance	$ 65.7

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
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-2

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