Convertible Preferred Stock Warrant - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended				0 Months Ended			12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2008	Mar. 31, 2008 Series A Convertible Preferred Stock Hercules	Apr. 02, 2012 Common Stock	Apr. 12, 2012 Common Stock Hercules	Apr. 02, 2012 Common Stock Hercules	Mar. 31, 2013 Additional Paid-in Capital	Mar. 31, 2012 Additional Paid-in Capital
Convertible Preferred Stock Warrants [Line Items]
Conversion of warrants				80,560		80,560	80,560
Conversion of warrants exercise price			$ 8.07
Reclassification of convertible preferred stock warrant liability (Note 2)	$ (2,170)	$ 431						$ (2,170)	$ 431
Shares surrendered						17,367
Common stock shares issued					15,221,571	63,193