Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Allowance for receivables	$ 541,000	$ 490,000
Accumulated depreciation and depletion	$ 192,901,310	$ 183,868,729
Capital stock, par value	$ 2.5	$ 2.5
Capital stock, shares authorized	10,000,000	10,000,000
Capital stock, shares issued	2,599,382	2,599,532
Capital stock, shares outstanding	2,599,382	2,599,532
Class B Capital Stock [Member]
Capital stock, par value	$ 2.50	$ 2.5
Capital stock, shares authorized	10,000,000	10,000,000
Capital stock, shares issued	1,366,299	1,367,399
Capital stock, shares outstanding	1,366,299	1,367,399