Consolidated balance sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
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	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	27,931,601	24,453,523
Common stock, shares outstanding	26,156,757	22,658,679
Treasury stock, shares	1,774,844	1,774,844