Subsequent Events Related to the COVID-19 Pandemic (Details) - PPP loan $ in Millions	May 04, 2020 USD ($) item	Mar. 27, 2020 USD ($) item
Subsequent Event [Line Items]
Number of times of average monthly payroll costs \| item		2.5
Loan amount		$ 10.0
Interest rate		1.00%
Loan term		2 years
Period for principal and interest payments deferred		6 months
Percentage of guarantee by SBA		100.00%
Percentage of loan proceeds used for payroll expenses		75.00%
Percentage of loan proceeds used for other qualifying expenses		25.00%
Subsequent event
Subsequent Event [Line Items]
Number of applications received \| item	400
Excess of loan application received	$ 61.0
Fee income generated from loans	$ 1.9

The amount of fee income from loans.

No definition available.

Name:	asrv_FeeIncomeFromLoans
Namespace Prefix:	asrv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount of excess loan application received.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivableExcessOfLoanApplicationReceived
Namespace Prefix:	asrv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the interest rate on loans receivable.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivableInterestRate
Namespace Prefix:	asrv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the term on loans receivable.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivableLoanTerm
Namespace Prefix:	asrv_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of applications received.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivableNumberOfApplicationsReceived
Namespace Prefix:	asrv_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of guarantee by SBA.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivablePercentageOfGuaranteeBySba
Namespace Prefix:	asrv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of loan proceeds used for other qualifying expenses.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivablePercentageOfLoanProceedsUsedForOtherQualifyingExpenses
Namespace Prefix:	asrv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of loan proceeds used for payroll expenses.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivablePercentageOfLoanProceedsUsedForPayrollExpenses
Namespace Prefix:	asrv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period for principal and interest payments deferred.

+ References

No definition available.

+ Details

Name:	asrv_LoansReceivablePeriodForPrincipalAndInterestPaymentsDeferred
Namespace Prefix:	asrv_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of times of average monthly payroll costs.

+ References

No definition available.

+ Details

Name:	asrv_NumberOfTimesOfAverageMonthlyPayrollCosts
Namespace Prefix:	asrv_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after fee received for commitment to originate or purchase, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922352-210448

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448

+ Details

Name:	us-gaap_FinancingReceivableAfterDeferredIncomeOffset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=asrv_PaycheckProtectionProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: