| Note 5 - Leases (Details Textual) | 3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
| Jun. 30, 2023  USD ($)  ft² | Jun. 30, 2022  USD ($) | Jun. 30, 2023  USD ($)  ft² | Jun. 30, 2022  USD ($) | |
| Operating Lease, Payments | $ | $ 331,000 | $ 315,000 | $ 676,000 | $ 637,000 | 
| HONG KONG | ||||
| Area of Land (Square Foot) | 7,300 | 7,300 | ||
| Rolling Hills Estates [Member] | ||||
| Area of Land (Square Foot) | 4,900 | 4,900 | ||
| Richmond, British Columbia [Member] | ||||
| Area of Land (Square Foot) | 1,600 | 1,600 | ||
| Metuchen, New Jersey [Member] | ||||
| Area of Land (Square Foot) | 2,000 | 2,000 | ||
| CHINA | ||||
| Lessee, Number of Branches | 7 | 7 | ||
| X | ||||||||||
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- Definition Represents the lessees' number of branches. No definition available. 
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| X | ||||||||||
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- Definition Area of land held. No definition available. 
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| X | ||||||||||
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- Definition Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Details 
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- Details 
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| X | ||||||||||
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- Details 
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| X | ||||||||||
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- Details 
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| X | ||||||||||
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- Details 
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