Major Customers, Partnerships and Strategic Alliances - Agreement with Dow AgroSciences in Plant Agriculture - Additional Information (Detail) (Dow AgroSciences [Member], License agreement terms [Member], USD $)	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2005	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research program to develop laboratory research reagents	3 years
One-time license fee earned on exercise of option	$ 6,000,000
Royalty revenues	2,300,000
Percentage of royalties to be received from sublicensing	25.00%
Previously agreed research, development and commercialization milestone payments, and royalties on sales of products	4,000,000
Fee due	25,300,000
Minimum license annual fees specific reckoning period	11 years
Collaboration agreement related costs and expenses		0	0	0	0
Revenue attributable to research and development		0	0	0	0
Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual fees	250,000
Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual fees	$ 3,000,000