Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.05	$ 0.05
Common stock, authorized (in shares)	15,000,000	15,000,000
Common stock, issued (in shares)	10,886,036	10,838,747
Common stock, outstanding (in shares)	10,886,036	10,838,747