Note 10 - Dividends and Stock Repurchase Program (Details Textual) - $ / shares						1 Months Ended	3 Months Ended						6 Months Ended		12 Months Ended
	Jul. 23, 2020	Jun. 05, 2020	Apr. 23, 2020	Mar. 06, 2020	Jan. 23, 2020	Jul. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Jul. 18, 2019	Jul. 19, 2018
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share)		$ 0.0950		$ 0.0950			$ 0.095		$ 0.0950	$ 0.0950	$ 0.0925	$ 0.0925	$ 0.095	$ 0.0925
Common Stock, Dividends, Per Share, Declared (in dollars per share)			$ 0.0950		$ 0.0950
Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares)																	100,000	100,000
Treasury Stock, Shares, Acquired (in shares)							1,281	0			28,000	42,000	1,281	70,000	0	0
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)							$ 16.95				$ 17.09		$ 16.95	$ 17.29
Stock Issued During Period Treasury Stock Reissued Average Cost Per Share (in dollars per share)											$ 17.09	$ 17.43
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.0975
Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares)	100,000
Treasury Stock, Shares, Acquired (in shares)						21,854
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)						$ 15.63