XML 56 R45.htm IDEA: XBRL DOCUMENT
v3.25.1

SECURITIES AND OTHER INVESTMENTS (Schedule of Gross Unrealized Losses and Fair Value of Investments) (Details) - USD ($) $ in Thousands | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | $ 172,491 | $ 183,814
Less than 12 Months, Unrealized Losses | (2,085) | (2,542)
More than 12 Months, Fair Value | 1,682,990 | 1,696,552
More than 12 Months, Unrealized Losses | (385,460) | (403,433)
Total, Fair Value | 1,855,481 | 1,880,366
Unrealized Losses, Total | (387,545) | (405,975)
US Government Agencies Debt Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 0 | 1,935
Less than 12 Months, Unrealized Losses | 0 | (2)
More than 12 Months, Fair Value | 1,094 | 1,286
More than 12 Months, Unrealized Losses | (13) | (25)
Total, Fair Value | 1,094 | 3,221
Unrealized Losses, Total | (13) | (27)
US States and Political Subdivisions Debt Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 6,008 | 6,560
Less than 12 Months, Unrealized Losses | (377) | (322)
More than 12 Months, Fair Value | 434,789 | 444,056
More than 12 Months, Unrealized Losses | (137,351) | (129,381)
Total, Fair Value | 440,797 | 450,616
Unrealized Losses, Total | (137,728) | (129,703)
Corporate Bond Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 195 | 8,620
Less than 12 Months, Unrealized Losses | (1) | (27)
More than 12 Months, Fair Value | 152,758 | 145,655
More than 12 Months, Unrealized Losses | (7,533) | (9,292)
Total, Fair Value | 152,953 | 154,275
Unrealized Losses, Total | (7,534) | (9,319)
Commercial Mortgage-Backed Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 34,482 | 56,155
Less than 12 Months, Unrealized Losses | (939) | (1,547)
More than 12 Months, Fair Value | 181,760 | 181,990
More than 12 Months, Unrealized Losses | (42,594) | (45,241)
Total, Fair Value | 216,242 | 238,145
Unrealized Losses, Total | (43,533) | (46,788)
Residential Mortgage-Backed Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 131,806 | 110,544
Less than 12 Months, Unrealized Losses | (768) | (644)
More than 12 Months, Fair Value | 912,589 | 923,565
More than 12 Months, Unrealized Losses | (197,969) | (219,494)
Total, Fair Value | 1,044,395 | 1,034,109
Unrealized Losses, Total | (198,737) | (220,138)
Agency Securities [Member] | Commercial Mortgage-Backed Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 15,166 | 31,291
Less than 12 Months, Unrealized Losses | (83) | (359)
More than 12 Months, Fair Value | 161,498 | 160,880
More than 12 Months, Unrealized Losses | (41,527) | (44,319)
Total, Fair Value | 176,664 | 192,171
Unrealized Losses, Total | (41,610) | (44,678)
Agency Securities [Member] | Residential Mortgage-Backed Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 108,671 | 104,477
Less than 12 Months, Unrealized Losses | (571) | (546)
More than 12 Months, Fair Value | 886,146 | 895,714
More than 12 Months, Unrealized Losses | (195,106) | (216,208)
Total, Fair Value | 994,817 | 1,000,191
Unrealized Losses, Total | (195,677) | (216,754)
Non-agency | Commercial Mortgage-Backed Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 19,316 | 24,864
Less than 12 Months, Unrealized Losses | (856) | (1,188)
More than 12 Months, Fair Value | 20,262 | 21,110
More than 12 Months, Unrealized Losses | (1,067) | (922)
Total, Fair Value | 39,578 | 45,974
Unrealized Losses, Total | (1,923) | (2,110)
Non-agency | Residential Mortgage-Backed Securities [Member] |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Less than 12 months, Fair Value | 23,135 | 6,067
Less than 12 Months, Unrealized Losses | (197) | (98)
More than 12 Months, Fair Value | 26,443 | 27,851
More than 12 Months, Unrealized Losses | (2,863) | (3,286)
Total, Fair Value | 49,578 | 33,918
Unrealized Losses, Total | $ (3,060) | $ (3,384)

X
- Definition Amount of 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 more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: 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 3: 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_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: 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 3: 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_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 less than 12 months, 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_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 unrealized loss position, 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 6 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6B + Details
Name: | us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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

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

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

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

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=us-gaap_AgencySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=aub_NonAgencySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |