Stockholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended			9 Months Ended		1 Months Ended	9 Months Ended	3 Months Ended	1 Months Ended
	May 31, 2013	Sep. 30, 2014	Dec. 31, 2013	Mar. 21, 2014 Common Stock [Member]	Sep. 30, 2014 Series F Convertible Preferred Stock [Member]	Mar. 21, 2014 Series F Convertible Preferred Stock [Member]	Apr. 30, 2014 April 2014 Offering [Member]	Sep. 30, 2014 April 2014 Offering [Member]	Mar. 31, 2014 2014 Private Placement [Member]	Sep. 30, 2013 IPO [Member]	Aug. 31, 2013 IPO [Member]
Subsidiary, Sale of Stock [Line Items]
Common stock public offering							10,000,000
Common stock, shares issued							279,461				11,671,500
Common stock price per share							$ 6.00		$ 5.00		$ 4.00
Common stock price per share after deducting underwriting discounts and commissions							$ 5.64
Proceeds from issuance of common stock		$ 34,000	$ 21,000				$ 57,500,000			$ 41,100,000
Underwriting discounts							3,700,000			3,300,000
Offering costs							500,000			2,300,000
Lock in period for transfer of common stock								90 days
Number of common stock sold		33,609,212	21,310,614						4,000,000
Proceeds from private placement									20,000,000
Offering costs									1,400,000
Equity exchange stock issued				2,000,000
Equity exchange stock received						10,000
Equity exchange par or stated value		$ 1,000				$ 1,000
Conversion of preferred stock into common stock		2,000,000				200
Conversion price of common stock		$ 5.00
Beneficial ownership for conversion of preferred stock into common stock		9.99%
Beneficial conversion feature amount		14,800,000
Carrying value of preferred stock					24,832,000
Discount related to beneficial conversion feature					14,800,000
Increase in carrying value of preferred stock					$ 14,800,000
Common stock, shares authorized	500,000,000	500,000,000	500,000,000
Reverse stock split ratio	16.7