Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	10,000,000	10,000,000
Common stock, issued (in shares)	7,575,167	7,555,167
Common stock, outstanding (in shares)	7,166,998	7,156,281
Treasury stock, shares (in shares)	408,169	398,886
Series A Preferred Stock [Member]
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.50	$ 0.50
Preferred stock, authorized (in shares)	700,000	700,000
Preferred stock, outstanding (in shares)	0	0