Stockholders' Equity - Common and Preferred Shares - Additional Information (Detail) (USD $)	0 Months Ended				12 Months Ended			3 Months Ended
	May 28, 2014	Feb. 18, 2014	Sep. 23, 2013	Apr. 16, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2013	Sep. 30, 2013	Nov. 30, 2011
Stockholders' Equity - Common and Preferred Shares [Line Items]
Common stock authorized					70,000,000	70,000,000
Net proceeds from issuance of common stock and warrants	$ 14,822,000	$ 10,860,000
Gross proceeds from issuance of common stock and warrants	16,000,000	12,000,000
Exercise of warrants, shares of Company's common stock converted					1,054,625
Term of warrants	5 years 3 months 18 days	5 years
Exercise Price	$ 2.90	$ 2.75			$ 2.24
Percentage of warrants owned	4.99%	9.99%
Increase in percentage of warrants owned	9.99%
Number of warrant exercised					1,054,625
Proceeds from warrant exercises					9,512,000	864,000
Gross proceeds			5,800,000	5,000,000
Net proceeds			4,905,000	4,192,000
Number of common stock issued upon conversion				1,377,412
Number of preferred stock outstanding					0	0
Exercisable period of warrants					5 years
Purchase of common stock at closing					147,145
Non-cash deemed dividend to preferred stock						4,799,000
Proceeds from issuance of common stock, net of issuance costs					25,682,000	1,936,000	3,317,000
Issuance of common stock					20,705,000	5,586,000
Weighted average period for recognizing unrecognized compensation cost as expense					2 years 8 months 5 days
Unrecognized compensation cost related to stock option awards					515,000
Dividend yield					0.00%	0.00%	0.00%
Expense related to stock awards					414,000	679,000	511,000
Percentage of common stock at closing price					85.00%
Common stock issued under the 2009 ESPP					10,417
Officer [Member] | Restricted Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Number of restricted stock granted during period						72,933
Restricted stock granted during period value						199,913
2005 Plan [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Maximum number of shares acquired for the award of options, restricted stock and stock appreciation					833,333
Maximum number of shares granted to any one participant in any fiscal year					200,000
Number of participant					1
2005 Plan [Member] | Restricted Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Expense related to stock awards					20,000	259,913	0
Placement Agent and Related Persons [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Exercise Price					$ 2.80
Series A Preferred Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Common stock issued during period				5,000
Net proceeds			2,103,000
Number of preferred stock outstanding			2,802			0			2,802
Redeemable value of outstanding balance			2,802,000						2,802,000
Non-cash deemed dividend to preferred stock								2,480,000
Series B Preferred Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Common stock issued during period			5,800
Non-cash deemed dividend to preferred stock									2,310,000
Private Placement Series A Warrants [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Exercise of warrants, shares of Company's common stock converted				1,377,412
Exercise Price				$ 3.40	$ 3.4000
Exercisable period of warrants				5 years
Purchase of common stock at closing				82,645
Private Placement Series B Warrants [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Exercise of warrants, shares of Company's common stock converted				1,377,412
Exercise Price				$ 3.40	$ 3.4000
Proceeds from warrant exercises					1,118,000	864,000
Exercisable period of warrants				2 years
Warrant exercised					350,000	270,390
Public Offering [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Share price of common stock and warrants issued		$ 2.05
Number of warrants issued for each unit issued		0.5
Common stock issued during period		5,853,657
Exercise of warrants, shares of Company's common stock converted		2,926,829
Proceeds from warrant exercises					2,901,000
Common Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Common stock issued during period							294,000
Exercise of warrants, shares of Company's common stock converted					2,452,431
Proceeds from warrant exercises					5,493,000
Number of common stock issued upon conversion			2,452,431
Expense related to stock awards						1,000
Common Stock [Member] | Private Placement Series B Warrants [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Common stock issued during period					350,000	270,390
Registered Offering [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Share price of common stock and warrants issued	$ 2.9625
Number of warrants issued for each unit issued	0.5
Common stock issued during period	5,400,847
Exercise of warrants, shares of Company's common stock converted	2,700,424
Private Placement [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Exercise of warrants, shares of Company's common stock converted					0
Exercise Price	$ 3.7031	$ 2.56
Number of warrant exercised					2,452,431
Private Placement [Member] | Series A Preferred Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Number of preferred stock converted						2,198
Private Placement [Member] | Series B Preferred Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Number of common stock issued upon conversion						2,452,431
Number of preferred stock converted						5,800
Number of preferred stock outstanding					0
Private Placement [Member] | Public Offering [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Exercise of warrants, shares of Company's common stock converted		292,682
Private Placement [Member] | Common Stock [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Number of common stock issued upon conversion						605,422
Private Placement [Member] | Registered Offering [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Exercise of warrants, shares of Company's common stock converted	216,033
MLV & Co. LLC [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Common stock issued during period					0	422,000	178,000
Proceeds from issuance of common stock, net of issuance costs						1,936,000	1,270,000
Lincoln Park Capital Fund, LLC [Member]
Stockholders' Equity - Common and Preferred Shares [Line Items]
Common stock issued during period							294,000
Proceeds from issuance of common stock, net of issuance costs							2,047,000
Value of purchase agreement for the sale with Lincoln Park Capital Fund, LLC										$ 20,000,000
Purchase agreement date of expiration					January 11, 2015
Minimum purchase price per share										$ 6.00
Shares issued as a commitment fee							6,493
Issuance of common stock					0	0