Related-Party Transactions - Additional Information (Detail) (USD $)			1 Months Ended			1 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2011 Techne [Member]	Feb. 29, 2012 Techne [Member]	Feb. 29, 2012 Techne [Member] Private placement [Member]	Feb. 29, 2012 Techne [Member] Convertible notes payable [Member]	Sep. 30, 2013 GSK Agreement [Member]	Dec. 31, 2012 GSK Agreement [Member]
Related Party Transaction [Line Items]
Accounts receivable	$ 523,000	$ 1,156,000					$ 500,000	$ 1,200,000
Convertible loan principal amount			10,000,000
Convertible loan interest rate			5.00%
Convertible loan maturity date			2021-09
Outstanding, accrued, unpaid interest converted into common stock						1,021,490
Conversion price of common stock				$ 10.00
Warrant contractual term				10 years
Purchase of warrant common stock	150,000			150,000
Warrant common stock exercise price				20.00
Warrant common stock exercise price rate				200.00%
Parties purchased common stock					$ 5,000,000
Techne purchased common stock per share					$ 10.00