Note 17 - Stock-based Compensation - Restricted Stock (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of shares, unvested (in shares)	155,858	171,139	186,834
Unvested, grant date weighted average cost (in dollars per share)	$ 18.98	$ 16.63	$ 15.18
Number of shares, awarded (in shares)	51,122	52,898	59,595
Shares awarded, grant date weighted average cost (in dollars per share)	$ 25.78	$ 22.99	$ 19.41
Restrictions lapsed and shares released to employees/directors, number (in shares)	(49,265)	(61,205)	(67,086)
Restrictions lapsed and shares released to employees/directors, grant date weight-average cost (in dollars per share)	$ 17.98	$ 15.89	$ 15.13
Number of shares, forfeited (in shares)	(12,480)	(6,974)	(8,204)
Shares forfeited, grant date weighted average cost (in dollars per share)	$ 20.69	$ 18.97	$ 15.85
Number of shares, unvested (in shares)	145,235	155,858	171,139
Unvested, grant date weighted average cost (in dollars per share)	$ 21.57	$ 18.98	$ 16.63