Stockholders' Equity and Warrants - Additional Information (Detail) (USD $)	0 Months Ended		12 Months Ended
	Jan. 29, 2013	Feb. 25, 2009	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Nov. 01, 2013	Jun. 20, 2013
Stockholders Equity Note [Line Items]
Preferred stock, authorized			10,000,000		10,000,000
Common stock, authorized			450,000,000		450,000,000		240,000,000
Shares of common stock sold	16,489,893	14,378,698
Common stock purchase price	$ 19.60	$ 1.69
Net proceed from sale of common stock	$ 310,000,000	$ 22,800,000	$ 310,037,000
Warrants issued		10,784,024
Exercise price of warrants		$ 2.15				$ 20.00
Warrants exercised				5,805,843
Proceeds from warrants exercised				12,483,000
Adjustment of additional paid-up capital up on exercise of warrants				$ 87,000,000
Number of preferred share rights issued per share of common stock outstanding						1
Percentage of ownership that triggers rights separation from common stock						4.99%
Percentage of additional shares over 4.99% threshold that would trigger dilutive ownership events if acquired						0.50%
Series A Junior Preferred Stock
Stockholders Equity Note [Line Items]
Preferred stock, authorized					500,000
Preferred stock, voting rights					1,000 to 1 basis with each share of common stock.
Number of preferred share rights issued per share of common stock outstanding						0.001