Loans and Allowance for Loan Losses - Summary of Maturities of Loan Portfolio (Details) - Commercial Financial, Agricultural And Construction [Member]	Mar. 31, 2016 USD ($)
In one year or less	$ 28,662,284
After one year but within five years	36,094,654
After five years	23,746,360
Total	$ 88,503,298

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