XML 65 R49.htm IDEA: XBRL DOCUMENT
v3.24.0.1

SECURITIES AND OTHER INVESTMENTS (Narrative) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2023 USD ($) security | Dec. 31, 2022 USD ($) security
Schedule Of Debt Investments [Line Items] |  |
Available for sale securities past due or non-accrual | $ 0 | $ 0
Available for sale securities that had been in a continuous loss position for more than 12 months, Number of issues | security | 757 | 363
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss | $ 382,167,000 | $ 322,446,000
AFS securities in an unrealized loss, credit related impairment | 0 | 0
Available for sale securities, allowance for credit losses | 0 | 0
HTM securities past due or non accrual | 0 | 0
Restricted equity securities consist of Federal Reserve Bank stock | 67,000,000.0 | 67,000,000.0
Federal Home Loan Bank Stock | 48,400,000 | 53,200,000
Amortization of Tax Equity Investments | 4,800,000 | 4,100,000
Tax credits and savings on Tax Equity Investments | 5,700,000 | 4,900,000
Carrying value of Tax Equity Investments | 64,300,000 | 51,000,000.0
Unfunded commitments related to Tax Equity Investments | $ 39,500,000 | $ 27,800,000
Restricted equity securities as a percentage of outstanding borrowings, required by FHLB | 4.25% | 3.75%
Restricted equity securities as a percentage of outstanding borrowings, required by FRB | 6.00% | 6.00%
Held-to-Maturity Securities |  |
Schedule Of Debt Investments [Line Items] |  |
Accrued interest receivable | $ 8,400,000 | $ 8,600,000
Available-for-sale Securities |  |
Schedule Of Debt Investments [Line Items] |  |
Accrued interest receivable | $ 9,500,000 | $ 14,200,000
Non-agency collateralized mortgage obligations |  |
Schedule Of Debt Investments [Line Items] |  |
SSFA rating percentage | 20.00% | 20.00%

X
- Definition Amortization recognized during the period for tax equity investments. + References No definition available. + Details
Name: | aub_AmortizationOfTaxEquityInvestments
Namespace Prefix: | aub_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Debt Securities Available for Sale Nonaccrual. + References No definition available. + Details
Name: | aub_DebtSecuritiesAvailableForSaleNonaccrual
Namespace Prefix: | aub_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities, Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions. + References No definition available. + Details
Name: | aub_DebtSecuritiesAvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions
Namespace Prefix: | aub_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings and other comprehensive loss (OCI). + References No definition available. + Details
Name: | aub_ImpairmentLossOtherThanTemporaryDebtSecuritiesAvailableForSale
Namespace Prefix: | aub_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Restricted equity securities as a percentage of outstanding borrowings, required by Federal Home Loan Bank. + References No definition available. + Details
Name: | aub_RestrictedEquitySecuritiesAsPercentageOfOutstandingBorrowingsRequiredByFederalHomeLoanBank
Namespace Prefix: | aub_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Restricted equity securities as a percentage of outstanding borrowings, required by the Federal Reserve Bank. + References No definition available. + Details
Name: | aub_RestrictedEquitySecuritiesAsPercentageOfOutstandingBorrowingsRequiredByFederalReserveBank
Namespace Prefix: | aub_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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: | aub_ScheduleOfDebtInvestmentsLineItems
Namespace Prefix: | aub_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Simplified supervisory formula approach rating. + References No definition available. + Details
Name: | aub_SimplifiedSupervisoryFormulaApproachRating
Namespace Prefix: | aub_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Carrying value of Tax Equity Investments. + References No definition available. + Details
Name: | aub_TaxEquityInvestments
Namespace Prefix: | aub_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of tax credits and savings during the period on Tax Equity Investments. + References No definition available. + Details
Name: | aub_TaxEquityInvestmentsTaxCreditsAndSavings
Namespace Prefix: | aub_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Unfunded commitments related to Tax Equity Investments. + References No definition available. + Details
Name: | aub_TaxEquityInvestmentsUnfundedCommitments
Namespace Prefix: | aub_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount excluding accrued interest, of allowance for credit loss on 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 -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at amortized cost (held-to-maturity) on nonaccrual status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-16 + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityNonaccrual
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 325 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481026/942-325-45-1 + Details
Name: | us-gaap_FederalHomeLoanBankStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Federal Reserve Bank stock represents an equity interest in the Federal Reserve Bank. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 325 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481026/942-325-45-1 + Details
Name: | us-gaap_FederalReserveBankStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 946 -SubTopic 310 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480833/946-310-45-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(3)(a)(4)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_InterestReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_InformationByCategoryOfDebtSecurityAxis=us-gaap_HeldtomaturitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InformationByCategoryOfDebtSecurityAxis=aub_AvailableForSaleDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |