Note 6 - Redeemable, Convertible Preferred Stock - Schedule of Redeemable, Convertible Preferred Stock (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Redeemable, convertible preferred stock	$ 208	$ 203
Series B Preferred Stock [Member]
Redeemable, convertible preferred stock	96	95
Series C Preferred Stock [Member]
Redeemable, convertible preferred stock	$ 112	$ 108