Note 16 - Stock Repurchase Plan (Details Textual) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 01, 2008
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				1,000,000
Stock Repurchased and Retired During Period, Shares	0	45,100	0
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	216,575