Note 12 - Stock-based Compensation - Nonvested Option Shares and Changes (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Nonvested, beginning (in shares)	53,300	62,700
Price, beginning (in dollars per share)	$ 6.67	$ 6.14
Shares granted (in shares)	0	14,000
Price, granted (in dollars per share)	$ 0	$ 8.01
Shares forfeited (in shares)	(1,250)	(5,250)
Price, forfeited (in dollars per share)	$ 8.36	$ 7.22
Shares vested (in shares)	(19,900)	(18,150)
Price, vested (in dollars per share)	$ 5.94	$ 5.71
Nonvested, ending (in shares)	32,150	53,300
Price, ending (in dollars per share)	$ 7.09	$ 6.67