Commitments, Contingent Liabilities, and Financial Instruments with Off-Balance Sheet Risk - Contractual or Notional Amounts of Financial Instruments (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Notes to Financial Statements
Commitments to extend credit	$ 17,134,310SGB_CommitmentsToExtendCredit	$ 13,253,612SGB_CommitmentsToExtendCredit
Standby letters of credit and financial guarantees	$ 975,000	$ 50,000

Standby Letters Of Credit And Financial Guarantees

No definition available.

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