Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	$ 7,176	$ 6,871
Financing Receivable, Allowance for Credit Losses, Charge-offs	(416)	(100)
Financing Receivable, Allowance for Credit Losses, Recoveries	14	36
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	(402)	(64)
Provision for credit losses	2	(57)
Financing Receivable, Allowance for Credit Losses	6,776	6,750
Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	1,129	1,244
Financing Receivable, Allowance for Credit Losses, Charge-offs	(5)	(99)
Financing Receivable, Allowance for Credit Losses, Recoveries	0	28
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	(5)	(71)
Provision for credit losses	(438)	46
Financing Receivable, Allowance for Credit Losses	686	1,219
Municipal Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses, Charge-offs	0
Financing Receivable, Allowance for Credit Losses, Recoveries	0
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	0
Provision for credit losses	154
Financing Receivable, Allowance for Credit Losses	154
Construction And Land Development Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	1,304	1,059
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	0	0
Provision for credit losses	(610)	342
Financing Receivable, Allowance for Credit Losses	694	1,401
Commercial Real Estate Loans, Total [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	3,777	3,842
Financing Receivable, Allowance for Credit Losses, Charge-offs	(378)	0
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	(378)	0
Provision for credit losses	657	(689)
Financing Receivable, Allowance for Credit Losses	4,056	3,153
Residential Real Estate Loans, Total [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	837	588
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	(1)
Financing Receivable, Allowance for Credit Losses, Recoveries	2	2
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	2	1
Provision for credit losses	190	272
Financing Receivable, Allowance for Credit Losses	1,029	861
Consumer Installment and Revolving Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	129	138
Financing Receivable, Allowance for Credit Losses, Charge-offs	(33)	0
Financing Receivable, Allowance for Credit Losses, Recoveries	12	6
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	(21)	6
Provision for credit losses	49	(28)
Financing Receivable, Allowance for Credit Losses	$ 157	$ 116

No definition available.

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Namespace Prefix:	aubn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase in allowance for credit loss on financing receivable from recovery.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of writeoff of financing receivable, charged against allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
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-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (a)
-SubTopic 10
-Topic 230
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

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- Details

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