XML 47 R36.htm IDEA: XBRL DOCUMENT
v3.21.1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 USD ($) item | Dec. 31, 2020 USD ($)
Accounting Policies [Line Items] |  |
Number of bank branches | item | 129 |
Number of ATM's | item | 150 |
Goodwill | $ 935,560 | $ 935,560
Accrued interest receivable | 57,400 | 56,700
Available-for-sale Securities |  |
Accounting Policies [Line Items] |  |
Accrued interest receivable | 11,700 | 11,900
Held-to-maturity Securities |  |
Accounting Policies [Line Items] |  |
Accrued interest receivable | $ 5,100 | $ 6,800

X
- Definition [Line Items] for Accounting Policies [Table] + References No definition available. + Details
Name: | aub_AccountingPoliciesLineItems
Namespace Prefix: | aub_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of ATMs + References No definition available. + Details
Name: | aub_NumberOfAtms
Namespace Prefix: | aub_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of bank branches. + References No definition available. + Details
Name: | aub_NumberOfBankBranches
Namespace Prefix: | aub_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Interest, dividends, rents, ancillary and other revenues earned but not yet received by the entity on its investments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(4)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 2: 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)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(10)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
Name: | us-gaap_AccruedInvestmentIncomeReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + 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(10)(1)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266 + Details
Name: | us-gaap_Goodwill
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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