Loans and Allowance for Loan Losses - Summary of Maturities of Loan Portfolio (Details) - Commercial Financial, Agricultural And Construction [Member]	Sep. 30, 2015 USD ($)
In one year or less	$ 19,712,301
After one year but within five years	35,575,228
After five years	12,208,755
Total	$ 67,496,284

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