Redeemable Preferred Stock and Stockholders' Equity - Additional Information (Detail)

v3.21.1

Redeemable Preferred Stock and Stockholders' Equity - Additional Information (Detail)										1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 28, 2020 $ / shares	Jul. 23, 2020 USD ($) $ / shares shares	Jun. 10, 2020 USD ($) $ / shares	Nov. 05, 2019 USD ($) $ / shares shares	Oct. 29, 2019 USD ($) $ / shares shares	Nov. 14, 2018 Day $ / shares shares	Nov. 09, 2018 USD ($) Day $ / shares shares	Sep. 27, 2018 USD ($) $ / shares	Jan. 25, 2018 $ / shares shares	Mar. 31, 2020 USD ($) $ / shares shares	Sep. 30, 2019 shares	Dec. 31, 2020 USD ($) $ / shares shares	Jun. 30, 2020 shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) shares	Nov. 30, 2019 $ / shares	Oct. 31, 2019 $ / shares	Mar. 06, 2018 USD ($) $ / shares	Dec. 31, 2017 shares
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity preferred stock, shares authorized												1,000,000		1,000,000
Convertible preferred stock, shares issued and sold												0		70,000
Temporary equity preferred stock, shares outstanding												0		70,000
Preferred stock, shares issued												1,000		0
Common stock value | $												$ 98,000		$ 31,000
Deemed dividend on convertible preferred stock | $												$ 17,378,000
Series F Preferred stock, shares outstanding												1,000		0
Common stock, shares issued												97,708,502		31,439,000
Common stock, shares outstanding												97,663,419		31,439,000
Common stock, shares authorized												180,000,000		40,000,000
Share price | $ / shares																	$ 0.5750
Net proceeds from issuance of offering and private placement | $					$ 8,200,000
Dividend Declared | $												$ 0		$ 0	$ 0
Expected term (years)												5 years 6 months 3 days		5 years 11 months 19 days	5 years 10 months 13 days
Volatility												103.00%		85.00%	81.00%
Risk-free interest rate												0.37%		2.55%	2.54%
Change in fair value of warrants | $												$ (5,850,000)
Issuance costs for common stock warrants | $												$ 1,641,000
Other offering expenses | $			$ 700,000
Stock options outstanding												2,398,000		1,287,000	1,623,000				1,347,000
Stock Options
Temporary Equity And Stockholders Equity [Line Items]
Stock options granted												1,287,000		0
Stock options cancelled														124,000
Stock options outstanding														308,455
Stock Options | Employees
Temporary Equity And Stockholders Equity [Line Items]
Stock options granted									360,000
Awards valued per share | $ / shares									$ 2.11
Options expiration period									10 years
Options vesting description												The options vest ratably over the 36-month period, commencing on February 25, 2018
Share-based compensation arrangement vesting period									36 months
Stock option activity vesting commencement date									Feb. 25, 2018
Restricted Stock Units (RSUs)
Temporary Equity And Stockholders Equity [Line Items]
Granted or Issued												3,117,000		2,432,000	2,836,000
Restricted Stock Units (RSUs) | Boards
Temporary Equity And Stockholders Equity [Line Items]
Stock options granted												1,197,000		518,132
Restricted Stock Units (RSUs) | Mike DiTolla
Temporary Equity And Stockholders Equity [Line Items]
Stock options granted											98,738
2002 Stock Incentive Plan
Temporary Equity And Stockholders Equity [Line Items]
Common stock authorized for issuance												3,110,000
Common stock issued pursuant to options exercised												961,982
Options and restricted stock units outstanding												1,724,264
Options available for future grants												0
2018 Long-Term Incentive Plan
Temporary Equity And Stockholders Equity [Line Items]
Common stock authorized for issuance												12,221,000
Options and restricted stock units outstanding												2,024,000
Options available for future grants												439,000
2018 Long-Term Incentive Plan | Restricted Stock Units (RSUs) | Employees
Temporary Equity And Stockholders Equity [Line Items]
Granted or Issued												2,600,000		1,400,000
Units are subject to time-based vesting												355,000		715,000
Remaining awards vest based on certain Company performance criteria												710,000		685,000
Shares Issued AS Part Of Quarter Bonus Program												1,554,000		175,000
Deferred Compensation Plan
Temporary Equity And Stockholders Equity [Line Items]
Share based payment award, number of shares vested												714,000
Share based payment award, number of shares unvested and outstanding												1,617,000,000
Original Western Alliance Warrant
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares																		$ 2.35
Western Alliance Warrant
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares								$ 2.13
Warrants expire date								Sep. 27, 2028
SWK Warrants
Temporary Equity And Stockholders Equity [Line Items]
Share price | $ / shares												$ 0.39198
Exercise price of warrants | $ / shares							$ 1.34			$ 0.39198		$ 1.00				$ 1.00
Change in fair value of warrants | $							$ 400,000			$ 100,000
Warrants issued to purchase shares of common stock							372,023			487,198
Number of trading days of average closing price of common stock | Day							10
Warrants expire date							Nov. 09, 2026
Additional Warrants issued to purchase shares of common stock										63,779		63,779
DPG Warrants
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares						$ 1.34
Warrants issued to purchase shares of common stock						279,851
Number of trading days of average closing price of common stock | Day						10
Warrants expire date						Nov. 09, 2026
SWK Warrants and DPG Warrants
Temporary Equity And Stockholders Equity [Line Items]
Warrants issued to purchase shares of common stock												149,727		149,727
Weighted average exercise price of warrants | $ / shares												$ 2.17		$ 2.17
Convertible Preferred Stock
Temporary Equity And Stockholders Equity [Line Items]
Common stock, shares issued												97,709,000		31,439,000	21,072,000				20,468,000
Sale of common stock, shares												10,800,000		8,993,000
June 2020 Warrants
Temporary Equity And Stockholders Equity [Line Items]
Proceeds of common stock and warrants | $												$ 6,200,000
Exercise price of warrants | $ / shares												$ 0.42
Expected term (years)												5 years
Closing price of common stock | $ / shares												$ 0.54
Volatility												109.80%
Risk-free interest rate												0.45%
Dividend yield												0.00%
Allocation to preferred stock and warrants before issuance costs | $												$ 3,000,000
Allocation to common stock and warrants before issuance costs | $												$ 3,900,000
Maximum
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity preferred stock, shares authorized												1,000,000
Maximum | Original Western Alliance Warrant
Temporary Equity And Stockholders Equity [Line Items]
Warrants issued to purchase shares of common stock equal value | $																		$ 120,000
Maximum | Western Alliance Warrant
Temporary Equity And Stockholders Equity [Line Items]
Warrants issued to purchase shares of common stock equal value | $								$ 120,000
Maximum | SWK Warrants
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares												$ 0.8767
Maximum | DPG Warrants
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares												1.4197
Minimum | SWK Warrants
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares												1.34
Minimum | DPG Warrants
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares												$ 2.17
Series E Convertible Preferred Stock
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity preferred stock, shares authorized												69,565
Temporary equity numbers of shares sold														69,565
Conversion Of Preferred Stock Into Common Stock														6,956,500
Temporary equity net proceeds from conversion to common stock | $														$ 4,000,000
Convertible preferred stock, shares issued and sold												0		69,565
Temporary equity preferred stock, shares outstanding												0		69,565
Convertible preferred stock, shares issued upon conversion					100									100
Convertible preferred stock, conversion price per share | $ / shares					$ 0.5750
Series F Preferred Stock
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity preferred stock, shares authorized												18,000
Preferred stock, shares issued		18,000
Common stock value | $												$ 1,000
Conversion price | $ / shares												$ 0.40
Proceeds from issuance of equity securities | $												$ 18,000,000
Broker fees and related expenses | $												1,900,000
Proceeds of common stock and warrants | $		$ 18,000,000
Proceeds from issuance of warrants | $												2,700,000
Proceeds allocated to the warrants based upon fair values | $												$ 2,700,000
Series F Preferred stock, shares outstanding												882,000
Allocation to preferred stock and warrants before issuance costs | $												$ 2,700,000
Series F Preferred Stock | Rights Offering
Temporary Equity And Stockholders Equity [Line Items]
Proceeds allocated to the warrants based upon fair values | $		$ 2,700,000
Sale of common stock, shares		18,000
July 2020 Warrants
Temporary Equity And Stockholders Equity [Line Items]
Warrant issued		45,000,000
Equity, Fair Value Adjustment | $												9,500,000
Change in fair value of warrants | $												(5,800,000)
Allocation to preferred stock and warrants before issuance costs | $												15,300,000
Issuance costs for common stock warrants | $												1,600,000
July 2020 Warrants | Rights Offering
Temporary Equity And Stockholders Equity [Line Items]
Warrant issued		45,000,000
Allocated to the warrants based upon fair values | $		$ 15,300,000
Exercise price of warrants | $ / shares		$ 0.40
Series F Convertible Preferred Stock and July 2020 Warrants | Rights Offering
Temporary Equity And Stockholders Equity [Line Items]
Deemed dividend on convertible preferred stock | $												$ 14,700,000
Exercise price of warrants | $ / shares												$ 0.34
Expected term (years)												5 years
Closing price of common stock | $ / shares												$ 0.44
Volatility												109.80%
Risk-free interest rate												0.27%
Dividend yield												0.00%
Series F Preferred Stock and July Two Thousand Twenty Amendment
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares	$ 0.21
Expected term (years)	5 years
Closing price of common stock | $ / shares	$ 0.28
Volatility	109.50%
Risk-free interest rate	0.26%
Dividend yield	0.00%
Private Placement
Temporary Equity And Stockholders Equity [Line Items]
Gross proceeds from issuance of convertible preferred stock | $					$ 4,000,000
Private Placement | Series E Convertible Preferred Stock
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity numbers of shares sold													69,565
Conversion Of Preferred Stock Into Common Stock												6,956,500
Temporary equity net proceeds from conversion to common stock | $												$ 4,000,000
Convertible preferred stock, shares issued and sold					69,565
Common stock, shares issued												2,205,000
Share price | $ / shares					$ 57.50									$ 57.50
Convertible preferred stock, shares issued upon conversion												882
Public Offering
Temporary Equity And Stockholders Equity [Line Items]
Proceeds from issuance of common stock | $					$ 4,200,000
Warrant expiration date			Jun. 10, 2025
Proceeds from offering | $			$ 6,900,000
Combined purchase price of share and warrant | $ / shares			$ 0.64
Public Offering | Convertible Preferred Stock
Temporary Equity And Stockholders Equity [Line Items]
Sale of common stock, shares					7,820,000
Share price | $ / shares					$ 0.5750
Over-Allotment Option
Temporary Equity And Stockholders Equity [Line Items]
Proceeds from issuance of equity securities | $				$ 600,000
Sale of common stock, shares				1,173,000
Share price | $ / shares				$ 0.5750
Over-Allotment Option | Maximum
Temporary Equity And Stockholders Equity [Line Items]
Option to purchase additional common stock granted					1,173,000