Note 10 - Stockholders' Equity (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Aug. 02, 2021	Mar. 05, 2020
Capital Units, Authorized (in shares)	620,000,000
Common Stock, Shares Authorized (in shares)	600,000,000	600,000,000
Preferred Stock, Shares Authorized (in shares)	20,000,000
Preferred Stock, Shares Outstanding, Ending Balance (in shares)	0	0
Preferred Stock, Shares Issued, Total (in shares)	0	0
Stock Repurchase Program, Authorized Amount				$ 50,000,000
Stock Repurchased During Period, Value	$ 26,021,519	$ 28,502,946
Share Repurchase Program Authorized 2020 [Member]
Stock Repurchased During Period, Shares (in shares)	3,200,000
Stock Repurchased During Period, Value	$ 21,500,000
New Repurchase Authorization [Member]
Stock Repurchase Program, Authorized Amount			$ 50,000,000
Stock Repurchased During Period, Shares (in shares)	600,000
Stock Repurchased During Period, Value	$ 4,500,000