Collaboration and License Agreement - Additional Information (Detail)				1 Months Ended	9 Months Ended	12 Months Ended	1 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2013 USD ($)	Sep. 30, 2013 EUR (€)	Sep. 30, 2013 Exchange Rate [Member] USD ($)	Dec. 31, 2006 Merck Sharp [Member] USD ($)	Sep. 30, 2013 Merck Sharp [Member] USD ($)	Dec. 31, 2010 Merck Sharp [Member]	Jun. 30, 2010 Merck KGaA [Member]	Feb. 29, 2008 Merck KGaA [Member] USD ($)	Sep. 30, 2013 Merck KGaA [Member] EUR (€) Installment	Sep. 30, 2013 Merck KGaA [Member] USD ($)	Nov. 30, 2011 Merck KGaA [Member] November 30, 2011 Exchange Rate [Member] USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License fee paid to company				$ 20,000,000				$ 40,000,000
Proceeds from the sale of common stock under Stock Purchase Agreement				10,000,000
Common stock price	$ 1.55			$ 5.50
Aggregate potential milestones to be received under collaboration - one					165,000,000
Aggregate potential milestones to be received under collaboration - two					260,000,000
Extended revenue recognition period						2 years
Revenue Recognition Period						4 years
Research collaboration agreement, period				2 years
Maximum cumulative milestone revenue recognized in relation to the initiation of clinical trials or the achievement of preclinical milestones					1,000,000					12,100,000
Shares of common stock issued under stock purchase agreement				1,818,182
License fee received after foreign currency exchange rate in effect by company								39,700,000
Period of upfront payment revenue recognition							28 months
Aggregate payments under agreement excluding potential milestones									1,800,000	2,500,000
Number of monthly installments									10
Payments under agreement using exchange rate									1,000,000	1,300,000
Amount agreed to pay by the company on achievement of milestones		1,000,000	1,400,000
Final monthly installment									1
Maximum reimbursement agreed by the company									1,800,000		2,400,000
Payable termination agreement reimbursement	$ 1,100,000	€ 800,000