Note 20 - Subsequent Events (Details Textual) - USD ($) $ / shares in Units, $ in Millions			9 Months Ended	12 Months Ended	33 Months Ended
	Nov. 07, 2018	Oct. 25, 2018	Sep. 30, 2018	Dec. 31, 2017	Oct. 25, 2018	Nov. 08, 2018	Oct. 26, 2018	Feb. 01, 2016
Treasury Stock, Shares, Acquired			0	0
February 2016 Repurchase Program [Member]
Stock Repurchase Program, Authorized Amount								$ 45.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 7.5	$ 7.5
February 2016 Repurchase Program [Member] | Subsequent Event [Member]
Treasury Stock, Shares, Acquired		200,326			1,580,904
Treasury Stock, Value, Acquired, Cost Method		$ 7.5
Treasury Stock Acquired, Average Cost Per Share					$ 28.46
October 2018 Repurchase Program [Member] | Subsequent Event [Member]
Treasury Stock, Shares, Acquired	255,000
Treasury Stock, Value, Acquired, Cost Method	$ 9.7
Stock Repurchase Program, Authorized Amount							$ 45.0
Treasury Stock Acquired, Average Cost Per Share	$ 38.26
Stock Repurchase Program, Remaining Authorized Repurchase Amount						$ 35.3