Note 12 - Share-based Compensation - Summary of Option Transactions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Outstanding Options (in shares)	946,546	1,118,058
Outstanding Options (in dollars per share)	$ 8.39	$ 6.63
Granted options (in shares)	172,862	153,618	397,218
Granted options (in dollars per share)	$ 16.53	$ 18.11
Exercised options (in shares)	(279,766)	(309,230)
Exercised options (in dollars per share)	$ 7.31	$ 6.90
Lapsed options (in shares)	(11,131)	(10,900)
Lapsed options (in dollars per share)	$ 5.92	$ 6
Cancelled options (in shares)	(3,260)	(5,000)
Cancelled options (in dollars per share)	$ 17.53	$ 11.22
Outstanding Options (in shares)	825,251	946,546	1,118,058
Outstanding Options (in dollars per share)	$ 10.46	$ 8.39	$ 6.63