XML 29 R18.htm IDEA: XBRL DOCUMENT v3.25.1

Securities (Tables)	3 Months Ended
	Mar. 31, 2025
Investments debt and equity securities [Abstract]
Available-for-sale Securities [Table Text Block]	1 year 1 to 5 5 to 10 After 10 Fair Gross Unrealized  Amortized (Dollars in thousands) or less years years years Value Gains Losses Cost March 31, 2025 Agency obligations (a) $ — 26,867 26,052 — 52,919 — 6,343 $ 59,262 Agency MBS (a) 1 19,998 16,181 136,407 172,587 — 24,700 197,287 State and political subdivisions — 1,625 7,763 7,574 16,962 — 2,836 19,798 Total available-for-sale $ 1 48,490 49,996 143,981 242,468 — 33,879 $ 276,347 December 31, 2024 Agency obligations (a) $ — 26,655 25,756 — 52,411 — 7,734 $ 60,145 Agency MBS (a) 10 19,863 14,904 138,899 173,676 — 28,901 202,577 State and political subdivisions — 966 8,244 7,715 16,925 — 2,901 19,826 Total available-for-sale $ 10 47,484 48,904 146,614 243,012 — 39,536 $ 282,548 (a) Includes securities issued by U.S. government agencies or government -sponsored entities. Expected lives of these  securities may differ from contractual maturities because (i) issuers may have the right to call or repay such securities obligations with or without prepayment penalties and (ii) borrowers of the loans included in Agency MBS generally  have the right to prepay such loan in whole or in part at any time.
Available-for-sale Securities, Continuous Unrealized Loss Position [Table Text Block]	Less than 12 Months 12 Months or Longer Total Fair Unrealized Fair Unrealized Fair Unrealized (Dollars in thousands) Value Losses Value Losses Value Losses March 31, 2025: Agency obligations  $ — — 52,919 6,343 $ 52,919 6,343 Agency MBS 2 — 172,585 24,700 172,587 24,700 State and political subdivisions 1,772 42 14,840 2,794 16,612 2,836 Total  $ 1,774 42 240,344 33,837 $ 242,118 33,879 December 31, 2024: Agency obligations  $ — — 52,411 7,734 $ 52,411 7,734 Agency MBS 7 — 173,669 28,901 173,676 28,901 State and political subdivisions 1,798 17 14,776 2,884 16,574 2,901 Total  $ 1,805 17 240,856 39,519 $ 242,661 39,536

X

- References

No definition available.

+ Details

Name:	aubn_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTableTextBlock
Namespace Prefix:	aubn_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments.

+ References

No definition available.

+ Details

Name:	us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

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