Note 13 - Excess Tax Benefit Reclassification (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Cash Provided by (Used in) Operating Activities	$ 121,879,000	$ 133,801,000	$ 128,670,000
Net Cash Provided by (Used in) Financing Activities	$ (11,258,000)	(36,457,000)	(3,278,000)
Accounting Standards Update 2016-09 [Member]
Net Cash Provided by (Used in) Operating Activities		235,000	432,000
Net Cash Provided by (Used in) Financing Activities		$ (235,000)	$ (432,000)