Common Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified			1 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Feb. 28, 2014 Hercules [Member]
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Common stock, shares authorized	200,000,000	200,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares issued	103,361,000	102,523,000
Common stock, shares outstanding	103,361,000	102,523,000
Warrants exercised to purchase common stock			302,143
Proceeds from exercise of warrant			$ 1.1