Pending Merger and Acquisition - Additional Information (Detail) (USD $)	0 Months Ended
Jan. 28, 2015 Location	Dec. 31, 2014
Business Acquisition [Line Items]
Number of banking locations	13abcb_NumberOfServiceBankingLocations
Purchase price	$ 50,000,000
Reported assets of Coastal Bank		473,000,000
Reported loans of Coastal Bank		214,000,000
Reported deposits of Coastal Bank		336,000,000
Bank of America [Member]
Business Acquisition [Line Items]
Number of branches	18
Deposits acquired	$ 864,000,000
Deposit premium	3.00%

Business combination recognized identifiable assets acquired and liabilities assumed deposit liabilities.

No definition available.

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- Definition

Business combination recognized identifiable assets acquired and liabilities assumed deposits.

+ References

No definition available.

+ Details

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- Definition

Business combination recognized identifiable assets acquired and liabilities assumed long term debt.

+ References

No definition available.

+ Details

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- Definition

Deposit premium on deposits assumed.

+ References

No definition available.

+ Details

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- Definition

Number Of Bank Branches

+ References

No definition available.

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- Definition

Number of service banking locations.

+ References

No definition available.

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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- Definition

Amount of assets acquired at the acquisition date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

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