Note 6 - Income Taxes (Details Textual) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Deferred Tax Assets, Net	$ 581.9	$ 589.5
Deferred Tax Assets, Valuation Allowance	584.2	$ 591.7
SPO [Member]
Deferred Tax Assets, Net	66.8
Deferred Tax Assets, Valuation Allowance	$ 66.8

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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