Note 12 - Share-based Compensation - Summary of Information About Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Lower Range of Exercise Prices on options (in dollars per share)	$ 3.82
Upper Range of Exercise Prices on options (in dollars per share)	$ 18.66
Options outstanding (in shares) | shares	825,251
Weighted Average Remaining Contractual Life on options (Year)	3 years 138 days
Weighted Average Exercise Price on options (in dollars per share)	$ 10.46
Exercise Price Range 1 [Member]
Lower Range of Exercise Prices on options (in dollars per share)	3.82
Upper Range of Exercise Prices on options (in dollars per share)	$ 5.55
Options outstanding (in shares) | shares	74,166
Weighted Average Remaining Contractual Life on options (Year)	2 years 343 days
Weighted Average Exercise Price on options (in dollars per share)	$ 4.75
Exercise Price Range 2 [Member]
Lower Range of Exercise Prices on options (in dollars per share)	5.65
Upper Range of Exercise Prices on options (in dollars per share)	$ 7.36
Options outstanding (in shares) | shares	388,685
Weighted Average Remaining Contractual Life on options (Year)	2 years 10 days
Weighted Average Exercise Price on options (in dollars per share)	$ 6.47
Exercise Price Range 3 [Member]
Lower Range of Exercise Prices on options (in dollars per share)	7.96
Upper Range of Exercise Prices on options (in dollars per share)	$ 10.38
Options outstanding (in shares) | shares	62,800
Weighted Average Remaining Contractual Life on options (Year)	4 years 255 days
Weighted Average Exercise Price on options (in dollars per share)	$ 9.30
Exercise Price Range 4 [Member]
Lower Range of Exercise Prices on options (in dollars per share)	16.35
Upper Range of Exercise Prices on options (in dollars per share)	$ 18.66
Options outstanding (in shares) | shares	299,600
Weighted Average Remaining Contractual Life on options (Year)	4 years 350 days
Weighted Average Exercise Price on options (in dollars per share)	$ 17.28