FINANCING AGREEMENTS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	May 02, 2012	May 16, 2014
Financing arrangements
Outstanding balance		$ 7,234,983
Total long-term debt	4,805,341	4,879,090
Current maturities of long-term debt	(732,835)	(632,176)
Long-term debt - net of current maturities	4,072,506	4,246,914
Future maturity requirements for long-term debt
2015	732,835
2016	645,752
2017	637,835
2018	793,625
2019	270,067
Future	1,725,227
Total long-term debt	4,805,341	4,879,090
Line of credit
Financing arrangements
Maximum borrowing capacity			13,500,000
Variable rate basis	three-month LIBOR
Interest rate margin on variable rate basis (as a percent)	2.50%
Interest rate (as a percent)	2.75%
Weighted-average interest rate (as a percent)	2.90%
Outstanding balance	7,998,184	7,234,983
Unused availability supported by entity's borrowing base	5,100,000
Real estate term note
Financing arrangements
Variable rate basis	three-month LIBOR
Interest rate margin on variable rate basis (as a percent)	3.00%
Interest rate (as a percent)	3.25%
Weighted-average interest rate (as a percent)	3.40%
Real estate term note maturing on March 31, 2027
Financing arrangements
Debt instrument, face amount			1,800,000
Real estate term note expiring on May 31, 2012
Financing arrangements
Debt instrument, face amount			1,700,000
Term loan
Financing arrangements
Long-term debt - net of current maturities	300,000
Term loan | Maximum
Financing arrangements
Debt instrument, face amount			1,000,000
Term loan maturing on May 31, 2018
Financing arrangements
Debt instrument, face amount				1,000,000
Equipment loan maturing on May 31, 2018
Financing arrangements
Debt instrument, face amount				1,600,000
Industrial revenue bond payable to the City of Blue Earth, Minnesota
Financing arrangements
Interest rate (as a percent)	0.24%
Amount of annual principal payments	80,000
Total long-term debt	360,000	440,000
Future maturity requirements for long-term debt
Total long-term debt	360,000	440,000
Equipment notes maturing in May 2015
Financing arrangements
Variable rate basis	three-month LIBOR
Interest rate margin on variable rate basis (as a percent)	3.00%
Interest rate (as a percent)	3.25%
Amount of monthly principal payments	27,000
Total long-term debt	1,569,781	1,333,463
Future maturity requirements for long-term debt
Total long-term debt	1,569,781	1,333,463
Real estate term notes
Financing arrangements
Variable rate basis	three-month LIBOR
Total long-term debt	2,875,560	3,105,627
Future maturity requirements for long-term debt
Total long-term debt	$ 2,875,560	$ 3,105,627