Note 5 - Benefit Plans - Stock Option Activity (Details)	6 Months Ended
	Jun. 30, 2016 $ / shares shares
Incentive Stock Options [Member]
Balance outstanding as of January 1, 2016 (in shares)	91,500
Granted (in shares)
Exercised (in shares)	(11,500)
Forfeited (in shares)	(5,000)
Balance outstanding as of June 30, 2016 (in shares)	75,000
Options exercisable as of June 30, 2016 (in shares)	75,000
Non Incentive Stock Options [Member]
Balance outstanding as of January 1, 2016 (in shares)	57,500
Granted (in shares)
Exercised (in shares)	(5,000)
Forfeited (in shares)
Balance outstanding as of June 30, 2016 (in shares)	52,500
Options exercisable as of June 30, 2016 (in shares)	52,500
Balance outstanding as of January 1, 2016 (in dollars per share) | $ / shares	$ 19.58
Granted (in dollars per share) | $ / shares
Exercised (in dollars per share) | $ / shares	5.20
Forfeited (in dollars per share) | $ / shares	28.34
Balance outstanding as of June 30, 2016 (in dollars per share) | $ / shares	21.10
Options exercisable as of June 30, 2016 (in dollars per share) | $ / shares	$ 21.10