Loans and Allowance for Loan Losses - Summary of Maturities of Loan Portfolio (Details) (Commercial Financial And Agricultural And Construction [Member], USD $)	Mar. 31, 2013
Commercial Financial And Agricultural And Construction [Member]
In one year or less	$ 16,775,774
After one year but within five years	32,802,920
After five years	5,677,686
Total	$ 55,256,380

Distribution Of Loans Which Are Due After One Year But Within Five Years

No definition available.

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Namespace Prefix:	SGB_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant