Consolidated balance sheets (Parenthetical) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	45,000,000	45,000,000
Common stock, shares issued	24,363,246	24,327,140
Common stock, shares outstanding	22,588,402	22,552,296
Treasury stock, shares	1,774,844	1,774,844