GENZYME STRATEGIC TRANSACTION (Details) - USD ($)		3 Months Ended			12 Months Ended
	Jan. 27, 2009	Mar. 31, 2014	Sep. 30, 2010	Mar. 31, 2010	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Jul. 24, 2015	Dec. 16, 2014	Apr. 02, 2014	Jun. 21, 2013
Revenue Recognition
Sale of common stock (in shares)					88,626,042		96,674,786
Common stock, par value (in dollars per share)	$ 0.01				$ 0.01		$ 0.01
Price of common stock (in dollars per share)							$ 9.23	$ 25.50	$ 25.75	$ 12.75	$ 12.35
License fee revenue		$ 294,000			$ 294,000	$ 4,144,000
Collaboration License And Purchase Agreement | Genzyme Corporation
Revenue Recognition
Total agreed consideration amount	$ 18,500,000
Proceeds from Genzyme Collaboration, License and Purchase Agreement	16,650,000		$ 934,000	$ 962,000
Amount subject to holdback	$ 1,850,000
Initial collaboration period	5 years
Sale of common stock (in shares)	3,000,000
Price at which share of common stock are sold (in dollars per share)	$ 2.00
Aggregate purchase price	$ 6,000,000
Premium above closing price of common stock at which shares are sold (in dollars per share)	$ 0.51
Price of common stock (in dollars per share)	$ 1.49
Aggregate premium received over the closing price of common stock	$ 1,530,000
License fee revenue					$ 300,000	$ 4,100,000