FAIR VALUE MEASURES - Significant Unobservable Inputs Used in Fair Value Measurement of Level 3 Assets and Liabilities (Details) $ in Thousands	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt securities available for sale, at fair value	$ 579,204	$ 592,621
Other real estate owned, at fair value	1,910	3,810
Fair Value, Measurements, Recurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt securities available for sale, at fair value	1,350	1,380
Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral-dependent loans, at fair value	25,510	44,181
Other real estate owned, at fair value	399
Mortgage servicing rights	$ 232,236	$ 206,944
Discounted par values \| Discount rate \| Fair Value, Measurements, Recurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt securities available for sale, measurement input	0.100	0.080
Discounted par values \| Discount rate \| Fair Value, Measurements, Recurring \| Weighted Average Daily Balance \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt securities available for sale, measurement input	0.100	0.080
Third-party appraisals and discounted cash flows \| Collateral discounts and discount rates \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral-dependent loans, measurement input	0.00%	0.00%
Third-party appraisals and discounted cash flows \| Collateral discounts and discount rates \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral-dependent loans, measurement input	50.00%	50.00%
Third-party appraisals and discounted cash flows \| Collateral discounts and discount rates \| Fair Value, Measurements, Nonrecurring \| Weighted Average Daily Balance \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral-dependent loans, measurement input	34.00%	39.00%
Third-party appraisals and sales contracts \| Collateral discounts and estimated costs to sell \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned, measurement input	0.15
Third-party appraisals and sales contracts \| Collateral discounts and estimated costs to sell \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned, measurement input	0.47
Third-party appraisals and sales contracts \| Collateral discounts and estimated costs to sell \| Fair Value, Measurements, Nonrecurring \| Weighted Average Daily Balance \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned, measurement input	0.21
Discounted cash flows \| Discount rate \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.10	0.09
Discounted cash flows \| Discount rate \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.11	0.10
Discounted cash flows \| Discount rate \| Fair Value, Measurements, Nonrecurring \| Weighted Average Daily Balance \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.10	0.09
Discounted cash flows \| Prepayment speed \| Fair Value, Measurements, Nonrecurring \| Minimum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.05	0.10
Discounted cash flows \| Prepayment speed \| Fair Value, Measurements, Nonrecurring \| Maximum \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.23	0.40
Discounted cash flows \| Prepayment speed \| Fair Value, Measurements, Nonrecurring \| Weighted Average Daily Balance \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage servicing rights measurement input	0.08	13

Collateral-Dependent Loans, Measurement Input

No definition available.

Name:	abcb_CollateralDependentLoansMeasurementInput
Namespace Prefix:	abcb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Mortgage Servicing Rights

+ References

No definition available.

+ Details

Name:	abcb_MortgageServicingRights
Namespace Prefix:	abcb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Mortgage Servicing Rights Measurement Input

+ References

No definition available.

+ Details

Name:	abcb_MortgageServicingRightsMeasurementInput
Namespace Prefix:	abcb_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

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

- Definition

Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Value of input used to measure real estate owned by financial institution by financial institution which is not directly related to its business.

+ References

+ Details

Name:	us-gaap_OtherRealEstateOwnedMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5162-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4437-111522

+ Details

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

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=abcb_ValuationDiscountedParValuesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=abcb_ValuationThirdPartyAppraisalsAndDiscountedCashFlowsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=abcb_MeasurementInputCollateralDiscountsAndDiscountRatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=abcb_ValuationThirdPartyAppraisalsAndSalesContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=abcb_MeasurementInputCollateralDiscountsAndEstimatedCostsToSellMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=abcb_DiscountedCashFlowsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPrepaymentRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: