Statements of Stockholders' Equity (USD $)	Total	Accumulated Deficit	Class C Special Shares	Common Stock
Balance at Dec. 31, 2008	$ 13,826,419	$ (71,906,660)	$ 391	$ 85,732,688
Balance (in shares) at Dec. 31, 2008			391,286	27,042,764
Issuance of common shares
Stock option expense	1,254,503			1,254,503
Stock warrant expense	64,103			64,103
Registered direct offerings of common shares and warrants, net	11,352,751			11,352,751
Registered direct offerings of common shares and warrants, net (in shares)				6,000,000
Issuance of common shares pursuant to Cell Genesys, Inc. transaction	36,800,043			36,800,043
Issuance of common shares pursuant to Cell Genesys, Inc. transaction (in shares)				20,219,804
Credit equity financing facility	60,343			60,343
Net loss	(47,527,768)	(47,527,768)
Balance at Dec. 31, 2009	15,830,394	(119,434,428)	391	135,264,431
Balance (in shares) at Dec. 31, 2009			391,286	53,262,568
Issuance of common shares
Stock option exercise	2,014			2,014
Stock option exercise (in shares)				1,334
Stock option expense	992,757			992,757
Stock warrant expense	65,529			65,529
Registered direct offerings of common shares and warrants, net	48,452,644			48,452,644
Registered direct offerings of common shares and warrants, net (in shares)				28,127,228
Net loss	(46,196,216)	(46,196,216)
Balance at Dec. 31, 2010	19,147,122	(165,630,644)	391	184,777,375
Balance (in shares) at Dec. 31, 2010			391,286	81,391,130
Issuance of common shares
Stock option exercise	32,442			32,442
Stock option exercise (in shares)				19,167
Warrant exercises - various	24,062			24,062
Warrant exercises - various (in shares)				8,750
Stock option expense	1,177,683			1,177,683
Stock warrant expense	204,980			204,980
Underwritten offering of common shares, net	44,961,137			44,961,137
Underwritten offering of common shares, net (in shares)				16,000,000
Registered direct offerings of common shares and warrants, net	23,876,370			23,876,370
Registered direct offerings of common shares and warrants, net (in shares)				12,199,482
Net loss	(51,608,504)	(51,608,504)
Balance at Dec. 31, 2011	$ 37,815,292	$ (217,239,148)	$ 391	$ 255,054,049
Balance (in shares) at Dec. 31, 2011			391,286	109,618,529