Stockholders' Equity - Additional Information (Detail)									1 Months Ended			12 Months Ended							16 Months Ended
	May 23, 2019 USD ($) yr $ / shares	Apr. 29, 2019 USD ($) $ / shares shares	Jan. 11, 2019 shares	Dec. 23, 2016 USD ($) shares	Sep. 22, 2016 USD ($) shares	Dec. 30, 2010 USD ($) $ / shares shares	Feb. 12, 2009 USD ($) shares	Feb. 04, 2008 $ / shares	Jan. 31, 2019 USD ($) shares yr	Jul. 31, 2011 shares	Jan. 31, 2011 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares $ / shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2015 shares	Dec. 31, 2014 shares	Dec. 31, 2013 shares	Dec. 31, 2011 USD ($) $ / shares shares	May 31, 2010 USD ($) shares	Jan. 01, 2019 shares	May 19, 2017 USD ($)	Dec. 29, 2010 $ / shares
Class of Stock [Line Items]
Common stock, shares authorized												100,000,000	100,000,000
Undesignated stock, shares authorized												20,000,000	20,000,000
Net proceeds from issuance of common stock | $												$ 50,469,000	$ 15,379,000
Warrants issued						500	6,000,000		3,579,642
Exercise price of warrant | $ / shares						$ 7.20
Fair market value of common stock per share | $ / shares	$ 4.01											$ 2.86
Common Stock, Value, Issued | $												$ 56,000	$ 41,000
Common Stock, Shares, Issued												56,894,642	41,190,905
Research and development expense | $												$ 7,467,000	$ 6,471,000
Minimum closing price of the common stock to require conversion | $ / shares																		$ 18.00
Stock issuance costs | $						$ 47,000
Preferred stock issuable							3,000,000
Preferred stock value | $							$ 6,000,000
Common shares issuable upon conversion of preferred stock							2,000,000											1,667
Number of shares agreed to issue and sell				1,008,000
Liquidation preference per share after series A preferred stock | $ / shares						$ 10,000
Preferred stock, par value | $ / shares																						$ 0.01
Recognition of non cash charge related to extension of warrants | $									$ 6,622,000			$ 6,622,000
Warrants Exercised												500,000								3,579,642
Price per warrants class | $ / shares						$ 7.20
Measurement Input, Price Volatility [Member] | Before Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability									9,800
Measurement Input, Price Volatility [Member] | After Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability									10,600
Measurement Input, Expected Dividend Rate | Before Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability									0
Measurement Input, Expected Dividend Rate | After Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability												0
Series A Preferred Stock
Class of Stock [Line Items]
Stock price per share | $ / shares								$ 9.00
Number of consecutive trading days prior to dividend payment date								20 days
Series A One Warrant
Class of Stock [Line Items]
Number of consecutive trading days prior to dividend payment date								15 days
Maximum | Minimum expected life range [member] | Before Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability | yr									1.33
Maximum | Minimum expected life range [member] | After Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability | yr									6.33
Maximum | Measurement Input, Risk Free Interest Rate [Member] | Before Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability									259
Maximum | Measurement Input, Risk Free Interest Rate [Member] | After Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability									260
Minimum | Minimum expected life range [member] | Before Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability | yr									5.09
Minimum | Minimum expected life range [member] | After Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability | yr									0.09
Minimum | Measurement Input, Risk Free Interest Rate [Member] | Before Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability									240
Minimum | Measurement Input, Risk Free Interest Rate [Member] | After Modification of Terms of Warrants [Member]
Class of Stock [Line Items]
Derivative liability									256
Warrant [Member]
Class of Stock [Line Items]
Exercise price of warrant | $ / shares		$ 7.00
Issuance of warrants, value | $	$ 8,200,000
Termination notice period																		30 days
Price per warrants class | $ / shares		$ 7.00
Warrant [Member] | Measurement Input, Price Volatility [Member]
Class of Stock [Line Items]
Fair value assumptions, Measurement Input	10,100
Warrant [Member] | Measurement Input, Risk Free Interest Rate [Member]
Class of Stock [Line Items]
Fair value assumptions, Measurement Input	233
Warrant [Member] | Measurement Input, Expected Term [Member]
Class of Stock [Line Items]
Fair value assumptions, Measurement Input | yr	7
Series B-3 8% convertible preferred stock
Class of Stock [Line Items]
Series A 12% convertible preferred stock, shares authorized												2,508,000	2,508,000
Series B-1 12% convertible preferred stock
Class of Stock [Line Items]
Convertible stock conversion ratio								1,200
Series B-2 12% convertible preferred stock
Class of Stock [Line Items]
Series A 12% convertible preferred stock, shares authorized												2,100,000
Series B-2 12% convertible preferred stock | Maximum
Class of Stock [Line Items]
Convertible preferred stock dividend | $																		$ 100,000
Series C 6% super dividend redeemable convertible preferred stock
Class of Stock [Line Items]
Convertible preferred stock, shares authorized												1,000	1,000
Shares of common stock issued						212					13
Preferred stock, dividend rate																		6.00%
Stock price per share | $ / shares						$ 10,000					$ 10,000
Number of consecutive trading days for conversion of preferred stock																		15 days
Aggregate stated value and proceeds | $						$ 2,120,000
Liquidation preference per share after series A preferred stock | $ / shares																		$ 10,000
Proceeds from issuance of preferred stock, net | $						$ 2,073,000					$ 130,000
Common stocks issued upon conversion of Preferred Stock													293,340	293,340		33,756	40,193	8,334
Post conversion dividend rights issued										5						20	24
Post conversion redemption right, return on investment multiplier amount | $																		$ 10,000
Preferred stock redemption price | $ / shares																		$ 3.00
Convertible preferred stock, redemption value | $												$ 8,652,000
Issuance of common stock (in shares)						212					13
Series C 6% super dividend redeemable convertible preferred stock | Series A Preferred Stock
Class of Stock [Line Items]
Dividend as percentage of net sales																		2.50%
Series C 6% super dividend redeemable convertible preferred stock | Series B One Preferred Stock
Class of Stock [Line Items]
Dividend as percentage of net sales																		1.25%
Series B-3 8% convertible preferred stock
Class of Stock [Line Items]
Series A 12% convertible preferred stock, shares authorized												2,508,000
Preferred stock, dividend rate												8.00%
Series A 12% convertible preferred stock
Class of Stock [Line Items]
Series A 12% convertible preferred stock, shares authorized												1,742,500
Preferred stock, dividend rate								12.00%				12.00%
Stock price per share | $ / shares								$ 6.00
Dividend, percentage of value weighted average share price								100.00%
Conversion of Series A to common stock															360,000
Series A 12% convertible preferred stock | Scenario 2
Class of Stock [Line Items]
Stock price per share | $ / shares								$ 12.00
Series A 12% convertible preferred stock | Minimum
Class of Stock [Line Items]
Minimum closing price of the common stock to require conversion | $ / shares								$ 18.00
Series B-1 12% convertible preferred stock
Class of Stock [Line Items]
Series A 12% convertible preferred stock, shares authorized												900,000	900,000
Shares of common stock issued																			900,000
Warrants issued																			1,800,000
Preferred stock, dividend rate												12.00%
Preferred stock value | $							$ 6,000,000
Issuance of common stock (in shares)																			900,000
Series B-2 12% convertible preferred stock
Class of Stock [Line Items]
Series A 12% convertible preferred stock, shares authorized												2,100,000	2,100,000
Shares of common stock issued																			2,100,000
Warrants issued																			4,200,000
Proceeds from issuance of equity | $																			$ 5,483,000
Preferred stock issuable							3,000,000
Common shares issuable upon conversion of preferred stock							2,000,000
Convertible preferred shares													50,000
Common stocks issued upon conversion of Preferred Stock													8,424
shares relating to prorated dividend prior conversion													90
Issuance of common stock (in shares)																			2,100,000
Series B redeemable convertible preferred stock
Class of Stock [Line Items]
Dividend, percentage of value weighted average share price												100.00%
Number of consecutive trading days prior to dividend payment date												20 days
Dividends accrue rate												15.00%
Common Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock, shares authorized												12,748,500
Shares of common stock issued		10,488,161
Net proceeds from issuance of common stock | $		$ 44,900,000
Conversion of Series A to common stock															60,888
Warrants Exercised		2,622,154
Issuance of common stock (in shares)		10,488,161
Other Agreements
Class of Stock [Line Items]
Warrants issued												290
Exercise price of warrant | $ / shares												$ 5.00
Research and development expense | $												$ 12,000
Price per warrants class | $ / shares												$ 5.00
Other Agreements | Vendor
Class of Stock [Line Items]
Common Stock, Shares, Issued												2,883
Other Agreements | Maximum
Class of Stock [Line Items]
Common Stock, Value, Issued | $														$ 100,000
B Three Securities Purchase Agreement
Class of Stock [Line Items]
Warrants to purchase common stock issued in agreeing not to sell any share for 18 months					875,000
B Three Securities Purchase Agreement | Maximum
Class of Stock [Line Items]
Warrants to purchase common stock					669,262
B Three Securities Purchase Agreement | Series B-3 8% convertible preferred stock
Class of Stock [Line Items]
Number of shares agreed to issue and sell					1,500,000
Aggregate stated value and proceeds | $					$ 1,500,000
Number of common stock issued upon conversion					892,349
2017 At Market Agreement
Class of Stock [Line Items]
Aggregate offering price | $																					$ 30,000,000
Commission to sales agent as a percentage of gross proceeds																					3.00%
Shares of common stock issued												662,459	669,714
Net proceeds from issuance of common stock | $												$ 2,930,000	$ 5,603,000
Issuance of common stock (in shares)												662,459	669,714
Amended B Three Securities Purchase Agreement | Maximum
Class of Stock [Line Items]
Warrants to purchase common stock				924,780
Amended B Three Securities Purchase Agreement | Series B-3 8% convertible preferred stock
Class of Stock [Line Items]
Number of shares agreed to issue and sell				1,008,000
Aggregate stated value and proceeds | $				$ 1,000,000
Number of common stock issued upon conversion				896,997
Ten X Fund LP [Member] | Common Stock [Member]
Class of Stock [Line Items]
Common stocks issued upon conversion of Preferred Stock			3,789,346
Ten X Fund LP [Member] | Series B1 B2 and B3 Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Convertible preferred shares			5,508,000