Preferred Stock - Additional Information (Detail) (USD $)	12 Months Ended	1 Months Ended			12 Months Ended	0 Months Ended	12 Months Ended
	Dec. 31, 2014	Apr. 30, 2012	Jan. 31, 2012	Feb. 28, 2011	Dec. 31, 2012	Dec. 17, 2013	Dec. 31, 2013	Dec. 02, 2014	Feb. 11, 2014
Class of Stock [Line Items]
Preferred stock, aggregate purchase price	$ 15,419,000
Shares of common stock into which warrants are exercisable								871,840
Warrant issued, exercise price								$ 11.47
Percentage of stock dividend	8.00%
In order to, among other things, amend the Company's Certificate of Incorporation or Bylaws
Class of Stock [Line Items]
Percentage vote of holders of outstanding shares of series A and series B preferred stock required	70.00%
In order to effect a liquidation, dissolution, sale or merger of the Company
Class of Stock [Line Items]
Percentage vote of holders of outstanding shares of series A and series B preferred stock required	80.00%
Minimum [Member]
Class of Stock [Line Items]
Proceeds from issuance of initial public offering	30,000,000
Initial public offering price per share	$ 5.00
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued		20,500,000	5,000,000	11,000,000
Preferred stock, price per share		$ 1.00	$ 1.00	$ 1.00
Proceeds from issuance of convertible preferred stock		20,500,000	5,000,000	11,000,000	25,391,000
Conversion price of preferred stock	$ 1.00
Percentage of preferred stock shares outstanding	80.00%
Preferred stock, liquidation preference per share	$ 1.00
Series A Convertible Preferred Stock [Member] | If the aggregate amount which the holders of series A and series B preferred stock would be entitled to receive exceeds $3.00 per share and $5.25 per share, respectively
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 3.00
Series B Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued						7,203,845
Preferred stock, price per share						$ 1.75
Proceeds from issuance of convertible preferred stock						7,600,000	8,837,000
Preferred stock, aggregate purchase price						12,600,000
Shares of common stock into which warrants are exercisable							202,472
Warrant issued, exercise price							$ 0.06
Proceeds received from issuance of warrants						1,400,000
Net loss applicable to common stockholders						163,000
Increase in net loss attributable to common stockholders due to accretion of discount, per share							$ 0.12
Increase in net loss attributable to common stockholders due to accretion of discount							163,000
Conversion price of preferred stock	$ 1.75
Preferred stock, liquidation preference per share	$ 1.75
Series B Convertible Preferred Stock [Member] | Cash [Member]
Class of Stock [Line Items]
Preferred stock, aggregate purchase price						9,000,000
Series B Convertible Preferred Stock [Member] | If the aggregate amount which the holders of series A and series B preferred stock would be entitled to receive exceeds $3.00 per share and $5.25 per share, respectively
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 5.25
Series B Convertible Preferred Stock [Member] | Convertible Notes [Member]
Class of Stock [Line Items]
Preferred stock, aggregate purchase price						$ 3,600,000
Series A and B Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Number of preferred stock converted into common stock									8,260,444