Financing Receivable, Excluding Accrued Interest, Additional Reserve Requirements For Charge-Offs

No definition available.

Name:	amtb_FinancingReceivableExcludingAccruedInterestAdditionalReserveRequirementsForChargeOffs
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Changes In Credit Quality And Macroeconomic Factors

+ References

No definition available.

+ Details

Name:	amtb_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossChangesInCreditQualityAndMacroeconomicFactors
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Percent Of Total Loans

+ References

No definition available.

+ Details

Name:	amtb_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPercentOfTotalLoans
Namespace Prefix:	amtb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Financing Receivable, Excluding Accrued Interest, Due To Loan Growth

+ References

No definition available.

+ Details

Name:	amtb_FinancingReceivableExcludingAccruedInterestDueToLoanGrowth
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Financing Receivable, Excluding Accrued Interest, Modified, Within The 12 Months Preceding

+ References

No definition available.

+ Details

Name:	amtb_FinancingReceivableExcludingAccruedInterestModifiedWithinThe12MonthsPreceding
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing Receivable, Excluding Accrued Interest, Reserves For Increase In Specific Reserve Allocations

+ References

No definition available.

+ Details

Name:	amtb_FinancingReceivableExcludingAccruedInterestReservesForIncreaseInSpecificReserveAllocations
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Financing Receivable, Individually Evaluated for Credit Loss, Minimum Balance Requirement

+ References

No definition available.

+ Details

Name:	amtb_FinancingReceivableIndividuallyEvaluatedForCreditLossMinimumBalanceRequirement
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Internal Risk Ratings, Loan Balance, Maximum

+ References

No definition available.

+ Details

Name:	amtb_InternalRiskRatingsLoanBalanceMaximum
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Internal Risk Ratings, Loan Balance, Minimum

+ References

No definition available.

+ Details

Name:	amtb_InternalRiskRatingsLoanBalanceMinimum
Namespace Prefix:	amtb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage, before allowance for credit loss, of financing receivable to total financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

+ Details

Name:	srt_FinancingReceivableBeforeAllowanceForCreditLossToTotalPercent
Namespace Prefix:	srt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable classified as current. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 948
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477011/948-310-45-1

+ Details

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

- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of financing receivable individually evaluated for credit loss. Excludes financing receivable collectively evaluated for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.5.a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480418/310-10-S99-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11C
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-11C

+ Details

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

- Definition

Amortized cost of financing receivable modified during period for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 33
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-33

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Accumulated amortized cost of financing receivable modified for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 33
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-33

Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481746/310-40-50-4

+ Details

Name:	us-gaap_FinancingReceivableModificationsRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 12: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 14: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 16: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 17: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 18: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 19: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 20: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 21: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 22: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-12

Reference 23: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 24: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-15

Reference 25: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-29

+ Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=amtb_IndividuallyEvaluatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=amtb_OwnerOccupiedLoansIndividuallyEvaluatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=amtb_OwnerOccupiedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	amtb_TriggeringEventAxis=amtb_WithSpecificReserveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	amtb_TriggeringEventAxis=amtb_UnsecuredCommercialLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=amtb_CommercialRealEstateAndCommercialPortfolioSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=amtb_SingleFamilyResidentialLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Allowance for Credit Losses - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Financing Receivable, Credit Quality Indicator [Line Items]
Allowance for credit loss, percent of total loans	1.27%		1.27%		1.20%
Provision for credit losses - loans	$ 5,750,000	$ 3,560,000	$ 12,500,000	$ 20,756,000
Net increase in specific reserve allocations	2,200,000		3,900,000
Additional reserve requirements for charge-offs and credit quality	800,000		7,200,000
Due to loan growth	800,000		(2,000,000.0)
Changes in credit quality and macro economic factors	2,000,000.0		3,400,000
Financing receivable, excluding accrued interest, modified, within the 12 months preceding	0	0	0	0
Troubled debt restructuring	0		0		$ 0
Investment in loans, net of unearned income, individually evaluated	251,500,000		251,500,000		259,300,000
Loans	6,743,066,000		6,743,066,000		$ 6,613,391,000
Individually Evaluated
Financing Receivable, Credit Quality Indicator [Line Items]
Individually evaluated loans, minimum balance requirement	$ 1,000,000		$ 1,000,000
Owner Occupied Loans, Individually Evaluated
Financing Receivable, Credit Quality Indicator [Line Items]
Unsecured commercial loans, percent	100.00%		100.00%		100.00%
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Provision for credit losses - loans	$ 3,145,000	(180,000)	$ 7,171,000	10,129,000
Recorded investment			0	0
Loans	1,488,182,000		1,488,182,000		$ 1,446,406,000
Commercial loans \| Owner Occupied Loans, Individually Evaluated
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	85,200,000		85,200,000		84,500,000
Commercial loans \| Owner Occupied Loans, Individually Evaluated \| Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	83,000,000.0		83,000,000.0
Commercial loans \| Owner Occupied Loans, Individually Evaluated \| Owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,100,000		2,100,000
Commercial loans \| Owner Occupied Loans, Individually Evaluated \| With Specific Reserve
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	3,600,000		3,600,000		2,400,000
Commercial loans \| Owner Occupied Loans, Individually Evaluated \| Unsecured Commercial Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	0		0		200,000
Commercial Real Estate and Commercial Portfolio Segments
Financing Receivable, Credit Quality Indicator [Line Items]
Internal risk ratings, loan balance, minimum			3,000,000
Real estate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Provision for credit losses - loans	1,691,000	$ 2,117,000	1,279,000	$ 6,370,000
Loans	4,959,733,000		4,959,733,000		4,772,853,000
Real estate loans \| Single-family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Internal risk ratings, loan balance, maximum			3,000,000
Loans	$ 1,954,193,000		$ 1,954,193,000		$ 1,515,181,000