Note 4 - Shareholders' Equity (Details Textual) - At The Market Program [Member] - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Apr. 28, 2022
Number of Shares Authorized for Issuance (in shares)		152,800,000	200,000,000.0
Forward Sales Agreements, Proceeds If Settled		$ 16
Subsequent Event [Member]
Forward Sales Agreements, Shares (in shares)	228,690