Note 7 - Segment Information - Net Sales for Geographic Areas (Details) - USD ($)	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Net sales	$ 20,149,845	$ 20,672,227
UNITED STATES
Net sales	17,282,664	17,727,629
CANADA
Net sales	1,773,510	1,741,756
All Other Countries [Member]
Net sales	$ 1,093,671	$ 1,202,842

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration