Allowance for Loan Loss (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	$ 4,851	$ 4,750	$ 4,790	$ 4,757
Financing Receivable, Allowance for Credit Losses, Charge-offs	(131)	(18)	(147)	(115)
Financing Receivable, Allowance for Credit Losses, Recoveries	87	53	164	143
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	(44)	35	17	28
Provision for loan losses	0	0	0	0
Financing Receivable, Allowance for Credit Losses	4,807	4,785	4,807	4,785
Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	726	600	778	653
Financing Receivable, Allowance for Credit Losses, Charge-offs	(128)	0	(128)	(52)
Financing Receivable, Allowance for Credit Losses, Recoveries	59	13	83	59
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	(69)	13	(45)	7
Provision for loan losses	28	(69)	(48)	(116)
Financing Receivable, Allowance for Credit Losses	685	544	685	544
Construction And Land Development Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	781	787	700	734
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0	0	0
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	0	0	0	0
Provision for loan losses	(51)	49	30	102
Financing Receivable, Allowance for Credit Losses	730	836	730	836
Commercial Real Estate Loans, Total [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	2,287	2,197	2,218	2,126
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0	0	(39)
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0	1	0
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	0	0	1	(39)
Provision for loan losses	67	44	135	154
Financing Receivable, Allowance for Credit Losses	2,354	2,241	2,354	2,241
Residential Real Estate Loans, Total [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	904	1,017	946	1,071
Financing Receivable, Allowance for Credit Losses, Charge-offs	(1)	(11)	(1)	(15)
Financing Receivable, Allowance for Credit Losses, Recoveries	12	19	59	52
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	11	8	58	37
Provision for loan losses	(25)	(28)	(114)	(111)
Financing Receivable, Allowance for Credit Losses	890	997	890	997
Consumer Installment and Revolving Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	153	149	148	173
Financing Receivable, Allowance for Credit Losses, Charge-offs	(2)	(7)	(18)	(9)
Financing Receivable, Allowance for Credit Losses, Recoveries	16	21	21	32
Financing Receivable Allowance For Credit Losses Net Chargeoffs Recoveries	14	14	3	23
Provision for loan losses	(19)	4	(3)	(29)
Financing Receivable, Allowance for Credit Losses	$ 148	$ 167	$ 148	$ 167

No definition available.

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

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

+ Details

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

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

+ 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 direct write-downs of financing receivables charged against the allowance.

+ References

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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