Revenue - Additional Information (Details) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended			12 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Oct. 31, 2010 Vulcan Incorporated	Dec. 31, 2012 Vulcan Incorporated	Dec. 31, 2011 Vulcan Incorporated	Dec. 31, 2013 Vulcan Incorporated	Dec. 31, 2011 Life Sciences Discovery Fund Authority	Dec. 31, 2012 Life Sciences Discovery Fund Authority	Oct. 31, 2010 Life Sciences Discovery Fund Authority	Dec. 31, 2013 Small Business Innovative Research	Dec. 31, 2012 Small Business Innovative Research	Dec. 31, 2011 Small Business Innovative Research
Revenue [Line Items]
Grants received				$ 20,000,000
Deferred revenue				8,200,000	4,700,000	2,000,000	970,000	2,000,000	624,000
Maximum contractual amount from grant										5,000,000
Grant revenue recognized											630,000	721,000	266,000
Reduction of equipment cost basis due to assets purchased with grant funding	0	60,000	1,689,000		60,000	38,000		1,700,000
Remaining available amount under grant											$ 1,200,000