Collaboration Agreement - Additional Information (Detail) (USD $)	1 Months Ended			3 Months Ended								12 Months Ended			1 Months Ended		12 Months Ended
	Dec. 31, 2013	Oct. 31, 2011	Apr. 30, 2010	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 Vendor Licensed_Program Candidate	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Celgene [Member]	Jul. 31, 2013 Series B Convertible Preferred Stock [Member]	Dec. 31, 2013 Series B Convertible Preferred Stock [Member]	Dec. 31, 2012 Series B Convertible Preferred Stock [Member]	Apr. 30, 2010 Series B Convertible Preferred Stock [Member]	Dec. 31, 2013 Series B Convertible Preferred Stock [Member] Celgene [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2013 Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amended collaboration expiration date			2014-04
Discovery phase years			2 years
Number of candidates confirmed by the Joint Research Committee												2
Portion of extension recognized in unbilled collaboration revenue	$ 476,000			$ 476,000								$ 476,000
Number of licensed programs type under collaboration agreements												3
Period considered for agreement termination notice												90 days
Upfront payment received												121,200,000
Series B convertible preferred stock, purchased	0			0				0				0	0				0	5,190,551	5,190,551	5,190,551
Series B convertible preferred stock price per share																	$ 1.70
Net proceeds of Series B convertible preferred stock																	8,800,000
Additional consideration under agreement																	3,100,000
Reserve stock split												1-for-2.75					1-for-2.75
Reserve stock split ratio																	2.75
Additional outstanding shares common stock																1,887,473
Number of vendors selling similar competitive products												0
Revenue to be recognized from performance obligation												124,300,000
Number of years company expected to fulfill its performance obligations												6 years
Term of the initial discovery period before amendment to extend	4 years	3 years
Term of extended period after amendment of the initial discovery period	5 years	4 years
Payment made in pursuant to the amendment		20,000,000													20,000,000
Discovery phase of the strategic collaboration extended by															1 year
Recognized revenue to extension	500,000
Eligible payment to be received from extension of the discovery phase																					20,000,000
Date of extension of discovery phase	2016-04
Revenue				6,744,000	6,268,000	6,268,000	6,268,000	6,282,000	6,268,000	6,288,000	6,268,000	25,548,000	25,106,000	21,837,000
Receipts of potential milestone payments																					120,000,000
Milestone payment upon achievement of a specified clinical development milestone event																					25,000,000
Milestone payments upon achievement of specified regulatory milestone events																					70,000,000
Milestone payment upon achievement of a specified commercial milestone event																					25,000,000
Achievement of an early clinical development milestone event	22,500,000			22,500,000								22,500,000
Dosing of the last patient in a Company-sponsored	25,000,000			25,000,000								25,000,000
Potential milestone that the Company might be entitled to receive enrollment of the last patient																						5,000,000
Milestone or royalty payment received												$ 0