Note 8 - Share Repurchase Program (Details Textual)		3 Months Ended	12 Months Ended
	Aug. 13, 2020	Mar. 31, 2020 USD ($) shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 shares	Aug. 31, 2020 shares	Aug. 31, 2019 USD ($) shares
Stock Repurchase Program, Authorized Amount | $							$ 34,000,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares) | shares						2,700,000	1,800,000
Stock Repurchased and Retired During Period, Shares (in shares) | shares		53,064	0	0	0
Stock Repurchased and Retired During Period, Value | $		$ 597,000		$ 597,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount | $			$ 33,400,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased (in shares) | shares			2,600,000
Stock Split To [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	3
Stock Split from [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	2