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Note 5 - Balance Sheet Components (Details Textual) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Depreciation, Total			$ 114,000	$ 504,000	$ 476,000
Impairment of Property and Equipment		$ 106,000		1,272,000	106,000
Amortization of Intangible Assets, Total			1,732,000	2,320,000	2,727,000
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)					$ 1,600,000
In Process Research and Development 1 [Member]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 1,600,000
Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Remaining Life (Year)			8 years 328 days
Intellectual Property [Member]
Finite-Lived Intangible Asset, Useful Life (Year)			20 years
Finite-Lived Intangible Asset, Remaining Life (Year)			7 years
Minimum [Member] \| Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life (Year)			1 year 109 days
Maximum [Member] \| Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life (Year)			11 years 273 days
Restructuring Charges [Member]
Impairment of Right-of-use Asset				120,000
Restructuring Charges [Member] \| CALIFORNIA
Asset Impairment Charges, Total				$ 1,152,000