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

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Redeemable Preferred Stock and Stockholders' Equity - Additional Information (Detail)											1 Months Ended					3 Months Ended	6 Months Ended	12 Months Ended
	Feb. 28, 2021 USD ($)	Feb. 10, 2021 USD ($) $ / shares shares	Sep. 28, 2020 $ / shares	Jul. 23, 2020 USD ($) $ / shares shares	Jun. 10, 2020 USD ($) $ / shares shares	Nov. 05, 2019 USD ($) $ / shares shares	Oct. 29, 2019 USD ($) $ / shares shares	Nov. 14, 2018 d shares	Nov. 09, 2018 USD ($) d $ / shares shares	Sep. 27, 2018 USD ($) $ / shares	Sep. 30, 2020 $ / shares	Aug. 31, 2020 $ / shares	Mar. 31, 2020 USD ($) $ / shares shares	Nov. 30, 2019 $ / shares	Oct. 31, 2019 $ / shares	Sep. 30, 2019 shares	Jun. 30, 2020 $ / shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) $ / shares shares	May 31, 2019 $ / shares shares	Dec. 31, 2018 shares	Mar. 06, 2018 USD ($) $ / shares
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity preferred stock, shares authorized																		1,000,000
Temporary equity preferred stock, shares outstanding																		0	0
Allocated Share-based Compensation Expense | $																		$ 1,662,000	$ 3,370,000	$ 2,742,000
Preferred stock, shares issued																		0	1,000
Equity raise of gross proceeds | $		$ 14,400,000					$ 4,200,000
Common stock value | $																		$ 154,000	$ 98,000
Warrants adjusted exercise price | $ / shares																	$ 0.60
Allocated to the warrants based upon fair values | $					$ 3,900,000
Deemed dividend on convertible preferred stock | $																		$ 546,000	$ 17,378,000
Series F Preferred stock, shares outstanding																		0	1,000
Common stock, shares issued		14,000,000																153,721,000	97,709,000
Common stock, shares outstanding																		153,676,000	97,663,000
Common stock, shares authorized																		180,000,000	180,000,000	40,000,000
Share price | $ / shares		$ 1.03													$ 0.5750
Proceeds from issuance of common stock | $	$ 13,300,000																	$ 13,300,000
Expected term (years)																		6 years 1 month 6 days	5 years 6 months	6 years
Volatility																		111.00%	103.00%	85.00%
Risk-free interest rate																		1.00%	0.40%	2.60%
Change in fair value of warrants | $																		$ 0	$ (5,850,000)
Proceeds from the exercise of warrants | $																		16,562,000	46,000
Issuance costs for common stock warrants | $																		$ 0	$ 1,641,000
Other offering expenses | $					$ 700,000
Stock options granted																		0	0
Stock options outstanding																		1,738,000	2,398,000	1,287,000		1,623,000
Paid or declared dividends | $																		$ 0	$ 0	$ 0
Stock Options
Temporary Equity And Stockholders Equity [Line Items]
Stock options granted																		0	1,287,000	0
Stock options cancelled																		174,000
Stock options outstanding																		87,000
Restricted Stock Units (RSUs)
Temporary Equity And Stockholders Equity [Line Items]
Granted or Issued																		3,098,000	3,117,000	2,432,000
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
Phantom Share Units (PSUs) [Member]
Temporary Equity And Stockholders Equity [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period																		10,100,000
Allocated Share-based Compensation Expense | $																		$ 300,000
Stock Appreciation Rights (SARs) [Member]
Temporary Equity And Stockholders Equity [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period																		1,000,000.0
Allocated Share-based Compensation Expense | $																		$ 300,000
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																		1,000,000.0
Options and restricted stock units outstanding																		600,000
Options available for future grants																		0
2018 Long-Term Incentive Plan
Temporary Equity And Stockholders Equity [Line Items]
Common stock authorized for issuance																		36,900,000
Options and restricted stock units outstanding																		4,700,000
Increase in Number of Units Available for Issuance																		24,700,000
2018 Long-Term Incentive Plan | Restricted Stock Units (RSUs) | Employees
Temporary Equity And Stockholders Equity [Line Items]
Granted or Issued																		3,000,000.0	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																		1,200,000
Share based payment award, number of shares unvested and outstanding																		400,000
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]
Warrants adjusted strike price | $ / shares													$ 0.49	$ 1.00	$ 1.00
Warrants fair value assumptions, risk-free interest rate									3.13%
Warrants expiration period									8 years
Warrants fair value assumptions annual dividend per share | $ / shares									$ 0.00
Warrants fair value assumptions, expected volatility rate									81.79%
Exercise price of warrants | $ / shares									$ 1.34				$ 0.39
Change in fair value of warrants | $									$ 400
Warrants issued to purchase shares of common stock									372,023				487,198
Number of trading days of average closing price of common stock | d									10
Warrants expire date									Nov. 09, 2026
Additional Warrants issued to purchase shares of common stock													63,779
DPG Warrants
Temporary Equity And Stockholders Equity [Line Items]
Warrants fair value assumptions, risk-free interest rate									3.13%
Finder's fee | $									$ 400,000
Adjusted exercise price of warrants | $ / shares											$ 0.62	$ 0.38
Warrants expiration period									8 years
Warrants fair value assumptions annual dividend per share | $ / shares									$ 0.00
Warrants fair value assumptions, expected volatility rate									81.79%
Exercise price of warrants | $ / shares									$ 1.34
Change in fair value of warrants | $									$ 300,000
Warrants issued to purchase shares of common stock								279,851
Number of trading days of average closing price of common stock | d								10
Warrants expire date								Nov. 09, 2026
SWK Warrants and DPG Warrants
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares																					$ 2.17
Warrants issued to purchase shares of common stock																					149,727
Common Stock
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity preferred stock, shares outstanding																		153,721,000	97,709,000	31,439,000		21,072,000
Convertible Preferred Stock Converted to Common stock | $																		$ 600,000
Common stock, shares issued																		153,720,874
Common stock, shares outstanding																		153,675,791
Sale of common stock, net, shares					10,800,000													14,000,000	10,800,000
Exercise price of warrants | $ / shares					$ 0.515
Other offering expenses | $		$ 1,100
Common Stock | 2018 Long-Term Incentive Plan
Temporary Equity And Stockholders Equity [Line Items]
Options available for future grants																		2,500,000
June 2020 Warrants
Temporary Equity And Stockholders Equity [Line Items]
Proceeds of common stock and warrants | $																		$ 6,200,000
Dividend Declared | $																		$ 0
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%
Proceeds from the exercise of warrants | $																		$ 7,500,000	$ 0
Allocation to preferred stock and warrants before issuance costs | $																		3,000,000.0
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
Option to purchase additional common stock granted							1,173,000
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																		$ 0.88
Change in fair value of warrants | $													$ 100,000
Warrants issued to purchase shares of common stock									372,023,000
Maximum | DPG Warrants
Temporary Equity And Stockholders Equity [Line Items]
Exercise price of warrants | $ / shares																		1.42
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 | $																				$ 4,000,000.0
Convertible preferred stock, shares issued and sold																		0	0	69,565
Temporary equity preferred stock, shares outstanding																		0	0	70,000
Convertible preferred stock, shares issued upon conversion							100													100
Convertible preferred stock, conversion price per share | $ / shares							$ 0.5750
Series F Convertible Preferred Stock
Temporary Equity And Stockholders Equity [Line Items]
Temporary equity preferred stock, shares authorized				18,000														18,000
Temporary equity preferred stock, shares outstanding																		251	882
Common stock value | $				$ 1,000
Conversion price | $ / shares				$ 0.40
Proceeds from issuance of equity securities | $																		$ 18,000,000.0
Broker fees and related expenses | $																		1,900,000
Proceeds of common stock and warrants | $				$ 18,000,000.0
Proceeds from issuance of warrants | $																		2,700,000
Deemed dividend on convertible preferred stock | $				$ 2,700,000														$ 500,000
Sale of common stock, net, shares																		1,000	17,000
Convertible preferred stock, shares issued upon conversion				2,500
Allocation to preferred stock and warrants before issuance costs | $				$ 2,700,000
Series F Convertible 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, net, shares				18,000
July 2020 Warrants
Temporary Equity And Stockholders Equity [Line Items]
Warrant issued				45,000,000
Proceeds from issuance of warrants | $																		$ 15,300,000
Dividend yield																		0.00%
Equity, Fair Value Adjustment | $																			$ 9,500,000
Change in fair value of warrants | $																			(5,800,000)
Proceeds from the exercise of warrants | $																		$ 28,100,000	3,900,000
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%
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]
Convertible preferred stock, shares issued and sold							69,565
Share price | $ / shares							$ 57.50
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 | $																				$ 4,000,000.0
Share price | $ / shares																				$ 57.50
Private Placement | Series F Convertible Preferred Stock
Temporary Equity And Stockholders Equity [Line Items]
Convertible preferred stock, shares issued upon conversion																		251	882
Public Offering
Temporary Equity And Stockholders Equity [Line Items]
Sale of common stock, net, shares							7,820,000
Share price | $ / shares							$ 0.5750
Gross proceeds from issuance of convertible preferred stock | $							$ 4,000,000.0
Net proceeds from issuance of offering and private placement | $							$ 8,200,000
Warrant expiration date					Jun. 10, 2025
Proceeds from offering | $					$ 6,900,000
Combined purchase price of share and warrant | $ / shares					$ 0.64
Over-Allotment Option
Temporary Equity And Stockholders Equity [Line Items]
Share price | $ / shares						$ 0.5750
Option to purchase additional common stock granted						1,173,000
Gross proceeds from issuance of convertible preferred stock | $						$ 600,000