Note 11 - Stock-based Compensation (Details Textual) - USD ($)								12 Months Ended
	Mar. 02, 2022	Dec. 22, 2021	Nov. 01, 2021	Apr. 01, 2021	Feb. 12, 2020	Apr. 26, 2019	Dec. 31, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	May 08, 2019	Jan. 31, 2018	Oct. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)								7,123,000	7,503,000	8,013,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)								80,000	50,000
Share-based Payment Arrangement, Expense								$ 552,000	$ 3,072,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value								0	0
Stock Issued During Period, Shares, Issued for Services (in shares)						9,000,000.0
Share Price (in dollars per share)						$ 0.32
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture, Total						$ 2,900,000		$ 552,000	$ 1,750,000
Common Stock Awards, Unvested (in shares)							7,100,000
Common Stock Awards, Fair Value Per Share (in dollars per share)							$ 0.32
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures, Total (in shares)				1,500,000
Shares, Restricted Stock Award, Subject to Annual Forfeiture (in shares)				750,000
Series B Preferred Stock [Member]
Preferred Stock, Convertible, Shares Issuable (in shares)							6,980,000
Conversion of Membership Units Into Common Stock [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities (in shares)						71,000
Conversion of Membership Units Into Series B Convertible Preferred Stock [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities (in shares)							69,815
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate								0.90%	0.50%
Common Stock Awards [Member]
Share-based Payment Arrangement, Expense									$ 1,322,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value					$ 1,638,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate					1.44%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate					75.00%
APIC, Share-based Payment Arrangement, Increase for Cost Recognition, Total									(1,638,000)
Common Stock [Member]
Share-based Payment Arrangement, Expense								$ 376,000	$ 1,128,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)							2 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted (in shares)				1,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Granted				$ 65,000
The 2013 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)												1,200,000	200,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)						900,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number (in shares)								600,000
The 2019 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)		26,072,542									11,072,542
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)		15,000,000.0
Ownership Percentage		50.30%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)								80,000	50,000
Share-based Compensation Arrangement by Share-based Payment Award, Options Grant Date Fair Value								$ 12,000	$ 5,400
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total								$ 40,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)								2 years 8 months 12 days
Share-based Payment Arrangement, Expense								$ 151,000	$ 590,000
The 2019 Omnibus Incentive Plan [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures, Total (in shares)	5,800,000
The 2019 Omnibus Incentive Plan [Member] | Director [Member]
Stock Issued During Period, Shares, Issued for Services (in shares)			250,000
The 2019 Omnibus Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number (in shares)									600,000
Share-based Payment Arrangement, Accelerated Cost									$ 79,000
The 2019 Omnibus Incentive Plan [Member] | Restricted Stock [Member] | Director [Member]
Stock Issued During Period, Shares, Issued for Services (in shares)			250,000
Stock Issued During Period, Shares Subject to Forfeiture, Increments (in shares)			125,000
Stock Issued During Period, Value, Issued for Services			$ 12,775