CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Stockholders' equity:
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, authorized	20,000,000	20,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.0013	$ 0.0013
Common stock, authorized	160,000,000	160,000,000
Common stock, issued	69,856,025	69,832,949
Common stock, shares outstanding (in shares)	69,656,025	69,632,949
Treasury stock, shares	200,000	200,000