Note 5 - Stock-based Compensation (Details) - Restricted Stock Units - Restricted Stock [Member]	3 Months Ended
Mar. 31, 2016 shares
Note 5 - Stock-based Compensation (Details) - Restricted Stock Units [Line Items]
Balance at December 31, 2015	542,375
Balance at March 31, 2016	537,563
Vested	(4,812)

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant