Warrants - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended	0 Months Ended		12 Months Ended	0 Months Ended
	Dec. 31, 2014	Mar. 22, 2013	Sep. 26, 2014	Dec. 31, 2013	Jan. 17, 2012	Apr. 30, 2014	Apr. 14, 2014	Sep. 03, 2013
Class of Warrant or Right [Line Items]
Stock issued, price per share						$ 4.00	$ 4.00
Warrant, expiration period	7 years
Warrants outstanding								1,200,000
Stock Purchase Agreement 2013 [Member] | 2013 PIPE investors [Member]
Class of Warrant or Right [Line Items]
Number of investors		17
Stock issued, shares		2,420,000
Stock issued, price per share		$ 1.25
Proceeds from PIPE		$ 3.0
Warrants to purchase common shares		1,209,600
Warrants, exercise price		$ 1.65
Warrant, expiration period		5 years
Merger Agreement [Member]
Class of Warrant or Right [Line Items]
Exchange ratio								1.1533
Amended and Restated Loan Agreement [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price			$ 4.015
Warrant, expiration period	7 years
Warrants exercised	0
Common stock warrants issued			38,325
Related Parties [Member] | Stock Purchase Agreement 2013 [Member] | 2013 PIPE investors [Member]
Class of Warrant or Right [Line Items]
Stock issued, shares		1,280,000
Warrants to purchase common shares		640,000
Warrants exercised	10,000			54,000
Silicon Valley Bank and Oxford Finance LLC [Member]
Class of Warrant or Right [Line Items]
Warrants to purchase common shares					279,588
Warrants, exercise price					$ 1.45
Warrant, expiration period					10 years
Warrants exercised	0			139,794
Other expense					1.8
Stock issued due to exercise of options				112,766
Warrants Not Settleable in Cash [Member]
Class of Warrant or Right [Line Items]
Share-based compensation arrangement by share-based payment award, Equity instruments other than options, aggregate intrinsic value, outstanding	1.6			8.7