Assets Acquired in FDIC-Assisted Acquisitions - Changes in FDIC Shared-Loss Receivable (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Business Combinations [Abstract]
Beginning balance	$ 31,351us-gaap_FDICIndemnificationAsset	$ 65,441us-gaap_FDICIndemnificationAsset	$ 65,441us-gaap_FDICIndemnificationAsset
Payments received from FDIC	(6,390)	(6,773)	(22,494)
Accretion (amortization)	(3,666)	(8,203)	(18,449)
Changes in clawback liability	(569)	(164)	(1,222)
Charge-offs on covered loans	1,602abcb_ChargeOffsOnCoveredLoans	2,369abcb_ChargeOffsOnCoveredLoans	3,372abcb_ChargeOffsOnCoveredLoans
Write downs of covered other real estate	804	876	4,771
Reimbursable expenses on covered assets	651	483	1,078
Other activity, net	(471)	(848)	(1,146)
Ending balance	$ 23,312us-gaap_FDICIndemnificationAsset	$ 53,181us-gaap_FDICIndemnificationAsset	$ 31,351us-gaap_FDICIndemnificationAsset

Charge Offs On Covered Loans

No definition available.

Name:	abcb_ChargeOffsOnCoveredLoans
Namespace Prefix:	abcb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expenses On Covered Assets Reimbursable By Federal Deposit Insurance Corporation

+ References

No definition available.

+ Details

Name:	abcb_ExpensesOnCoveredAssetsReimbursableByFederalDepositInsuranceCorporation
Namespace Prefix:	abcb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Federal Deposit Insurance Corporation Clawback Liability

+ References

No definition available.

+ Details

Name:	abcb_FederalDepositInsuranceCorporationClawbackLiability
Namespace Prefix:	abcb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Federal Deposit Insurance Corporation Loss Share Receivable Accretion Amortization

+ References

No definition available.

+ Details

Name:	abcb_FederalDepositInsuranceCorporationLossShareReceivableAccretionAmortization
Namespace Prefix:	abcb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Federal Deposit Insurance Corporation Loss Share Receivable Other Activity Net

+ References

No definition available.

+ Details

Name:	abcb_FederalDepositInsuranceCorporationLossShareReceivableOtherActivityNet
Namespace Prefix:	abcb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_BusinessCombinationsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount of receivable assets originating from the indemnification agreement with the Federal Deposit Insurance Corporation (FDIC), in which the FDIC is to partially cover losses.

+ References

No definition available.

+ Details

Name:	us-gaap_FDICIndemnificationAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of decreases to the indemnification asset due to cash payments received relating to loss sharing agreements with the Federal Deposit Insurance Corporation (FDIC).

+ References

No definition available.

+ Details

Name:	us-gaap_FDICIndemnificationAssetCashPaymentsReceived
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Valuation adjustments made to other real estate covered by loss sharing agreements not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations that may also be included in real estate owned. Excludes real estate assets taken in settlement of troubled loans through surrender or foreclosure by banks.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherRealEstateCoveredValuationAdjustments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration