XML 103 R49.htm IDEA: XBRL DOCUMENT
v3.20.1

SECURITIES (Amortized Cost of HTM Securities by Security Type and Credit Rating) (Details) $ in Thousands | Mar. 31, 2020 USD ($)
--- | ---
HTM Securities, Amortized Cost | $ 552,176
Moody's AAA/AA/A | Standard & Poor's AAA/AA/A |
HTM Securities, Amortized Cost | 536,747
Moody's Not Rated - Agency [Member] | Standard Poors Not Rated - Agency [Member] |
HTM Securities, Amortized Cost | 8,659
Moody's Not Rated - Non-Agency [Member] | Standard Poors Not Rated - Non-Agency [Member] |
HTM Securities, Amortized Cost | 6,770
U.S. government and agency securities |
HTM Securities, Amortized Cost | 2,797
U.S. government and agency securities | Moody's AAA/AA/A | Standard & Poor's AAA/AA/A |
HTM Securities, Amortized Cost | 0
U.S. government and agency securities | Moody's Not Rated - Agency [Member] | Standard Poors Not Rated - Agency [Member] |
HTM Securities, Amortized Cost | 2,797
U.S. government and agency securities | Moody's Not Rated - Non-Agency [Member] | Standard Poors Not Rated - Non-Agency [Member] |
HTM Securities, Amortized Cost | 0
Obligations of states and political subdivisions |
HTM Securities, Amortized Cost | 543,517
Obligations of states and political subdivisions | Moody's AAA/AA/A | Standard & Poor's AAA/AA/A |
HTM Securities, Amortized Cost | 536,747
Obligations of states and political subdivisions | Moody's Not Rated - Agency [Member] | Standard Poors Not Rated - Agency [Member] |
HTM Securities, Amortized Cost | 0
Obligations of states and political subdivisions | Moody's Not Rated - Non-Agency [Member] | Standard Poors Not Rated - Non-Agency [Member] |
HTM Securities, Amortized Cost | 6,770
Total mortgage-back securities |
HTM Securities, Amortized Cost | 5,862
Total mortgage-back securities | Moody's AAA/AA/A | Standard & Poor's AAA/AA/A |
HTM Securities, Amortized Cost | 0
Total mortgage-back securities | Moody's Not Rated - Agency [Member] | Standard Poors Not Rated - Agency [Member] |
HTM Securities, Amortized Cost | 5,862
Total mortgage-back securities | Moody's Not Rated - Non-Agency [Member] | Standard Poors Not Rated - Non-Agency [Member] |
HTM Securities, Amortized Cost | $ 0

X
- Definition Amount, before other-than-temporary impairment (OTTI) accretion, of investment in debt securities measured at amortized cost (held-to-maturity). + References No definition available. + Details
Name: | us-gaap_HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | srt_CreditRatingMoodysAxis=aub_MoodysAaaAaRatingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CreditRatingStandardPoorsAxis=aub_StandardPoorsAaaAaRatingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CreditRatingMoodysAxis=aub_MoodySNotRatedAgencyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CreditRatingStandardPoorsAxis=aub_StandardPoorsNotRatedAgencyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CreditRatingMoodysAxis=aub_MoodySNotRatedNonAgencyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CreditRatingStandardPoorsAxis=aub_StandardPoorsNotRatedNonAgencyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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_MortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |