Note 13 - Stock-based Compensation and Similar Arrangements - Nonvested Stock Activity (Details) - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Non-vested at beginning of period (in shares) | shares	44,182
Non-vested at beginning of period (in dollars per share) | $ / shares	$ 38.67
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares	57,964
Granted (in dollars per share) | $ / shares	$ 44.90
Vested (in shares) | shares	(26,100)
Vested (in dollars per share) | $ / shares	$ 35.53
Forfeited or cancelled (in shares) | shares	(3,848)
Forfeited or cancelled (in dollars per share) | $ / shares	$ 44.63
Non-vested at end of period (in shares) | shares	72,198
Non-vested at end of period (in dollars per share) | $ / shares	$ 44.44