Loans and Allowance for Loan Losses - Summary of Maturities of Loan Portfolio (Details) - Commercial Financial, Agricultural And Construction [Member]	Sep. 30, 2016 USD ($)
In one year or less	$ 26,200,937
After one year but within five years	45,296,045
After five years	24,414,991
Total	$ 95,911,973

Distribution of loans which are due after one year but within five years..

No definition available.

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