Investment Securities (Details Narrative)	Mar. 31, 2013
Schedule of Investments [Abstract]
Percentage of debt securities unrealized losses depreciated on amortized cost basis	0.50%

Percentage Of Debt Securities Unrealized Losses Depreciated On Amortized Cost Basis

No definition available.

Name:	SGB_PercentageOfDebtSecuritiesUnrealizedLossesDepreciatedOnAmortizedCostBasis
Namespace Prefix:	SGB_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant