FHLB Advances and Other Borrowings (Schedule of Additional Collateral) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Advances from Federal Home Loan Banks [Abstract]
Average Daily Balance During the Year	$ 16,091	$ 14,722
Average Interest Rate During the Year	0.15%gabc_ShortTermDebtAverageInterestRate	0.20%gabc_ShortTermDebtAverageInterestRate
Maximum Month-end Balance During the Year	$ 20,973	$ 17,722
Weighted Average Interest Rate at Year-end	0.15%	0.20%

The calculated average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date.

No definition available.

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- Details

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- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.

+ References

No definition available.

+ Details

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- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, maximum month-end borrowings during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Industry Guide

-Number 3

-Section VII

-Subsection 2

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- Definition

Weighted average interest rate of short-term debt outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Subparagraph b

-Article 5

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