Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Property, buildings and equipment, accumulated depreciation	$ 24,249,607	$ 23,152,625
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.1	$ 0.1
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	27,813,772	27,813,772
Common stock, shares outstanding	25,451,354	25,451,354
Treasury stock, shares	2,362,418	2,362,418