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Note 5 - Restructuring and Other Charges - Changes in Accrued Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Beginning balance			$ 340				$ 0	$ 340	$ 0
Restructuring Charges, Total	$ 51	$ 197	55	$ 1,078	$ 161	$ 38	8
Cash payments								(573)	(333)
Balance				340				70	340
Severance and Other One-Time Termination Benefits [Member]
Restructuring Charges, Total								120	248
Other Restructuring [Member]
Restructuring Charges, Total								183	173
Subletting Costs of the Fremont CA Facility [Member]
Restructuring Charges, Total									153
Subletting Costs of the Mansfield MA Facility [Member]
Restructuring Charges, Total									99
EMS Segment Restructuring and Facility Consolidation [Member]
Beginning balance			233				0	233	0
Cash payments								(416)	(148)
Balance				233				0	233
EMS Segment Restructuring and Facility Consolidation [Member] \| Severance and Other One-Time Termination Benefits [Member]
Restructuring Charges, Total								0	69
EMS Segment Restructuring and Facility Consolidation [Member] \| Other Restructuring [Member]
Restructuring Charges, Total								183	159
EMS Segment Restructuring and Facility Consolidation [Member] \| Subletting Costs of the Fremont CA Facility [Member]
Restructuring Charges, Total									153
EMS Segment Restructuring and Facility Consolidation [Member] \| Subletting Costs of the Mansfield MA Facility [Member]
Restructuring Charges, Total									0
Executive Management Changes [Member]
Beginning balance			107				0	107	0
Restructuring Charges, Total									514
Cash payments								(157)	(125)
Balance				107				70	107
Executive Management Changes [Member] \| Severance and Other One-Time Termination Benefits [Member]
Restructuring Charges, Total								120	133
Executive Management Changes [Member] \| Other Restructuring [Member]
Restructuring Charges, Total								0	0
Executive Management Changes [Member] \| Subletting Costs of the Fremont CA Facility [Member]
Restructuring Charges, Total									0
Executive Management Changes [Member] \| Subletting Costs of the Mansfield MA Facility [Member]
Restructuring Charges, Total									99
Other Charges [Member]
Beginning balance			$ 0				$ 0	0	0
Cash payments								0	(60)
Balance				$ 0				0	0
Other Charges [Member] \| Severance and Other One-Time Termination Benefits [Member]
Restructuring Charges, Total								0	46
Other Charges [Member] \| Other Restructuring [Member]
Restructuring Charges, Total								$ 0	14
Other Charges [Member] \| Subletting Costs of the Fremont CA Facility [Member]
Restructuring Charges, Total									0
Other Charges [Member] \| Subletting Costs of the Mansfield MA Facility [Member]
Restructuring Charges, Total									$ 0