Note 14 - Share-based Payments - Stock Option Transactions (Details) - $ / shares	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Outstanding, Number of shares (in shares)	502,590	827,076	513,366	976,062
Outstanding, Weighted average exercise price per share (in dollars per share)	$ 11.30	$ 6.69	$ 9.24	$ 6.23
Granted, Number of shares (in shares)	18,750	22,500	81,750	67,500
Granted, Weighted average exercise price per share (in dollars per share)	$ 27.53	$ 24.96	$ 22.66	$ 21.26
Exercised, Number of shares (in shares)	(31,065)	(41,404)	(94,602)	(229,057)
Exercised, Weighted average exercise price per share (in dollars per share)	$ 3.80	$ 4.59	$ 3.75	$ 3.22
Forfeited, Number of shares (in shares)		(3,677)	(9,489)	(8,135)
Forfeited, Weighted average exercise price per share (in dollars per share)		$ 9.63	$ 17.23	$ 11.43
Expired, Number of shares (in shares)			(750)	(1,875)
Expired, Weighted average exercise price per share (in dollars per share)			$ 3.76	$ 2.40
Outstanding, Number of shares (in shares)	490,275	804,495	490,275	804,495
Outstanding, Weighted average exercise price per share (in dollars per share)	$ 12.39	$ 7.30	$ 12.39	$ 7.30
Options exercisable, Number of shares (in shares)	306,553	580,721	306,553	580,721
Options exercisable, Weighted average exercise price per share (in dollars per share)	$ 9.16	$ 4.85	$ 9.16	$ 4.85

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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