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v3.20.2

Note 1 - Basis of Presentation (Details Textual) | 9 Months Ended
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Sep. 30, 2020
BAMKO [Member] |
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest | 99.00%

X
- Definition The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership. + References No definition available. + Details
Name: | us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_OwnershipAxis=sgc_BAMKOMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |