Note 15 - Subsequent Events (Details Textual) - USD ($)			6 Months Ended
	Aug. 04, 2021	Jul. 16, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Common Stock, Par or Stated Value Per Share (in dollars per share)			$ 0.01		$ 0.01
Proceeds from Issuance of Common Stock			$ 2,113,000	$ 276,000
Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)		1,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.01
Shares Issued, Price Per Share (in dollars per share)		$ 54.50
Stock Issued During Period, Value, New Issues		$ 51,000,000.0
Subsequent Event [Member] | Underwriters [Member]
Stock Issued During Period, Value, New Issues	$ 150,000
Proceeds from Issuance of Common Stock	$ 7,600,000