Note 12 - Stock-based Compensation - Information about the Company's Outstanding Options and Exercisable Options (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Range of Exercise Price, upper limit (in dollars per share)	$ 147,750
Outstanding Shares (in shares) | shares	4.43
Outstanding Life (Year)	9 years 332 days
Outstanding Price (in dollars per share)	$ 115,600
Exercisable Shares (in shares) | shares	10.69
Range A [Member]
Range of Exercise Price, lower limit (in dollars per share)	$ 10
Range of Exercise Price, upper limit (in dollars per share)	$ 91,500
Outstanding Shares (in shares) | shares	5.96
Outstanding Life (Year)	6 years 54 days
Outstanding Price (in dollars per share)	$ 59,350
Exercisable Shares (in shares) | shares	5.63
Range B [Member]
Range of Exercise Price, lower limit (in dollars per share)	$ 17
Range of Exercise Price, upper limit (in dollars per share)	$ 27,000
Outstanding Shares (in shares) | shares	2.69
Outstanding Life (Year)	11 years 3 days
Outstanding Price (in dollars per share)	$ 27,000
Exercisable Shares (in shares) | shares	11.01
Range C [Member]
Range of Exercise Price, lower limit (in dollars per share)	$ 26
Range of Exercise Price, upper limit (in dollars per share)	$ 29,250
Outstanding Shares (in shares) | shares	1.25
Outstanding Life (Year)	20 years 237 days
Outstanding Price (in dollars per share)	$ 29,250
Exercisable Shares (in shares) | shares	20.65