Note 4 - Redeemable, Convertible Preferred Stock - Schedule of Redeemable, Convertible Preferred Stock (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Redeemable, convertible preferred stock	$ 212	$ 210
Series B Preferred Stock [Member]
Redeemable, convertible preferred stock	97	96
Series C Preferred Stock [Member]
Redeemable, convertible preferred stock	$ 115	$ 114

Carrying amount, attributable to parent, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 470
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+ Details