Note 12 - Employee Benefit Plans (Details) - Schedule of Shares Issued - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Benefit Plans (Details) - Employee Stock Purchase Plan [Line Items]
Shares	2,660	2,932	3,186
Minimum [Member]
Employee Benefit Plans (Details) - Employee Stock Purchase Plan [Line Items]
Price per share	$ 31.95	$ 26.73	$ 25.20
Maximum [Member]
Employee Benefit Plans (Details) - Employee Stock Purchase Plan [Line Items]
Price per share	$ 36.18	$ 28.35	$ 26.73