Note 19 - Earnings Per Share - Computation of Earnings Per Share (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income attributable to common shares	$ 11,574,000	$ 10,123,000	$ 9,446,000	$ 10,881,000	$ 7,979,000	$ 8,337,000	$ 7,343,000	$ 7,615,000	$ 42,024,000	$ 31,274,000	$ 31,913,000
Weighted average common shares outstanding (in shares)									16,600,612	16,478,968	16,292,086
Basic earnings per common share (in dollars per share)	$ 0.70	$ 0.61	$ 0.57	$ 0.66	$ 0.48	$ 0.51	$ 0.45	$ 0.46	$ 2.53	$ 1.90	$ 1.96
Net income	$ 11,574,000	$ 10,123,000	$ 9,446,000	$ 10,881,000	$ 7,979,000	$ 8,337,000	$ 7,343,000	$ 7,615,000	$ 42,024,000	$ 31,274,000	$ 31,913,000
Weighted average common shares outstanding for basic earnings per common share (in shares)									16,600,612	16,478,968	16,292,086
Add: Dilutive effects of share-based awards (in shares)									5,804	10,102	18,644
Average shares and dilutive potential common shares (in shares)									16,606,416	16,489,070	16,310,730
Diluted earnings per common share (in dollars per share)	$ 0.70	$ 0.61	$ 0.57	$ 0.66	$ 0.48	$ 0.51	$ 0.45	$ 0.46	$ 2.53	$ 1.90	$ 1.96