BALANCE SHEETS (Parenthetical)	Dec. 31, 2011 PerShare	Dec. 31, 2010 PerShare
Stockholders' equity
Preferred stock, par value (in dollars per share)	0.01	0.01
Preferred stock, shares authorized (in shares)	30,000,000	30,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common Stock, par value (in dollars per share)	0.001	0.001
Common Stock, shares authorized (in shares)	160,000,000	160,000,000
Common Stock, shares issued (in shares)	90,692,071	87,238,301
Common Stock, shares outstanding (in shares)	90,692,071	87,238,301
Class A Stock [Member]
Stockholders' equity
Common Stock, par value (in dollars per share)	0.001	0.001
Common Stock, shares authorized (in shares)	40,000,000	40,000,000
Common Stock, shares issued (in shares)	2,109,512	2,182,036
Common Stock, shares outstanding (in shares)	2,109,512	2,182,036