Common Stock Warrants - Additional Informational (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended		1 Months Ended
	Jul. 27, 2012	Jul. 18, 2011	Jul. 18, 2011	Mar. 31, 2014	Dec. 31, 2013
Schedule Of Common Stock [Line Items]
Shares of common stock exercisable through warrants	15,784,200
Warrants exercise price per share	$ 2.50
Warrants expiry date	July 27, 2017
Term of common stock warrant exercisable (years)	5 years	10 years
Fair value of warrant liabilities				$ 21,785	$ 30,849
Warrant exercisable to Healthcare Royalty, shares		225,000	225,000
Warrant exercisable to Healthcare Royalty, price per share (usd per share)		$ 9.00
Healthcare Royalty
Schedule Of Common Stock [Line Items]
Fair value of warrant liabilities				$ 371	$ 492