Employee Benefits and Retirement Plans - Pension Asset Allocation and Fair Value Measurement (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity	$ 2,754,951	$ 2,806,587
Equity, percentage	23.00%	24.00%
Fixed income	4,812,463SGB_FixedIncomeFairValueDisclosure	3,429,416SGB_FixedIncomeFairValueDisclosure
Fixed income, percentage	41.00%	29.00%
Total	7,567,414us-gaap_InvestmentOwnedAtFairValue	6,236,003us-gaap_InvestmentOwnedAtFairValue
Total, percentage	64.00%	53.00%
Certificates of deposit	3,260,260SGB_FairValueOfCertificateDeposits	4,783,837SGB_FairValueOfCertificateDeposits
Certificates of deposits, percentage	27.00%	40.00%
Cash and cash equivalent	1,062,004	799,456
Cash and cash equivalents, percentage	9.00%	7.00%
Total	4,322,264	5,583,293
Total, percentage	36.00%	47.00%
Fair value of plan assets	11,889,678	11,819,296	11,249,592	10,262,781
Fair value of plan assets, percentage	100.00%	100.00%
Level 1 [Member]
Equity	2,754,951	2,806,587
Fixed income	4,812,463	3,429,416
Total	7,567,414	6,236,003
Certificates of deposit	3,260,260	4,783,837
Cash and cash equivalent	1,062,004	799,456
Total	4,322,264	5,583,293
Fair value of plan assets	$ 11,889,678	$ 11,819,296

Estimated Fair Value Of Investment Of Assets

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Fair value of certificate deposits.

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Fixed Income Fair Value Disclosure

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Percentage Of Assets Estimated Fair Value In Investment

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Percentage Of Cash And Cash Equivalents Estimated Fair Value Portion

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Percentage Of Certificates Of Deposits Estimated Fair Value Portion

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Percentage Of Defined Benefit Plan Fair Value Of Plan Assets

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Percentage Of Equity Portion In Investment Fair Value

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Percentage Of Fixed Income Portion In Investment Fair Value

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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Fair value portion of investments accounted under the equity method.

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Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Percent of net assets at close of period. For schedules of investments that are categorized, each category has a percent of net assets for the aggregated value of the Investments in the category.

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