Statements of Stockholders' (Deficit) Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid In Capital	Treasury Stock	Other Comprehensive Income (Loss)	Accumulated Deficit	Other Comprehensive (Loss) Income
Balance at Dec. 31, 2008	$ (2,433)	$ 275	$ 169,854	$ (97)		$ (172,465)
Balance (in shares) at Dec. 31, 2008		27,522,931		85,550
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to the Genzyme Transaction (Note 3)	4,470	30	4,440
Issuance of common stock related to the Genzyme Transaction (Note 3) (in shares)		3,000,000
Issuance of common stock in private placement	8,062	43	8,019
Issuance of common stock in private placement (in shares)		4,315,792
Exercise of common stock options	732	4	728
Exercise of common stock options (in shares)		380,355
Issuance of common stock to fund the Company's 2010, 2009 and 2008 401(k) match	32		32
Issuance of common stock to fund the Company's 2010, 2009 and 2008 401(k) match (in shares)		24,430
Compensation expense related to issuance of stock options and restricted stock awards	1,426	4	1,422
Compensation expense related to issuance of stock options and restricted stock awards (in shares)		365,182
Compensation expense related to stock option modifications (Note 7)	1,155		1,155
Expense related to warrants (Note 4)	1,779		1,779
Treasury share retirement		(1)	(96)	97
Treasury share retirement (in shares)		(85,550)		(85,550)
Net loss	(9,128)					(9,128)	(9,128)
Other comprehensive (income) loss	(1)				(1)		(1)
Comprehensive income (loss)							(9,129)
Balance at Dec. 31, 2009	6,094	355	187,333		(1)	(181,593)
Balance (in shares) at Dec. 31, 2009		35,523,140
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of issuance costs of $1.5 and $5.6 million for 2011 and 2010, respectively	82,327	157	82,170
Issuance of common stock, net of issuance costs (in shares)		15,700,000
Exercise of common stock options and warrants	466	5	461
Exercise of common stock options and warrants (in shares)		528,937
Issuance of common stock to fund the Company's 2010, 2009 and 2008 401(k) match	65	1	64
Issuance of common stock to fund the Company's 2010, 2009 and 2008 401(k) match (in shares)		15,460
Compensation expense related to issuance of stock options and restricted stock awards	2,249	4	2,245
Compensation expense related to issuance of stock options and restricted stock awards (in shares)		396,092
Expense related to warrants (Note 4)	107		107
Net loss	(11,556)					(11,556)	(11,556)
Other comprehensive (income) loss	2				2		2
Comprehensive income (loss)							(11,554)
Balance at Dec. 31, 2010	79,754	522	272,380		1	(193,149)
Balance (in shares) at Dec. 31, 2010	52,163,629	52,163,629
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of issuance costs of $1.5 and $5.6 million for 2011 and 2010, respectively	27,215	36	27,179
Issuance of common stock, net of issuance costs (in shares)		3,593,750
Exercise of common stock options and warrants	685	7	678
Exercise of common stock options and warrants (in shares)		708,590
Issuance of common stock to fund the Company's 2010, 2009 and 2008 401(k) match	169		169
Issuance of common stock to fund the Company's 2010, 2009 and 2008 401(k) match (in shares)		27,872
Compensation expense related to issuance of stock options and restricted stock awards	4,255	1	4,254
Compensation expense related to issuance of stock options and restricted stock awards (in shares)		130,922
Expense related to warrants (Note 4)	107		107
Net loss	(28,675)					(28,675)	(28,675)
Other comprehensive (income) loss	(15)				(15)		(15)
Comprehensive income (loss)							(28,690)
Balance at Dec. 31, 2011	$ 83,495	$ 566	$ 304,767	$ 0	$ (14)	$ (221,824)
Balance (in shares) at Dec. 31, 2011	56,624,763	56,624,763