The percentage of after recoveries, of loans and leases that have been written-off.

No definition available.

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

- Definition

Represents the value of non performing assets.

+ References

No definition available.

+ Details

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

- Definition

Financing Receivable, Minimum Percent Required To Be Reviewed.

+ References

No definition available.

+ Details

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

- Definition

Financing Receivable, Threshold Balance Which Requires Quarterly Reviews.

+ References

No definition available.

+ Details

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

- Definition

Financing Receivable, Allowance For Credit Losses, Threshold For Individually Evaluating Of Impairment.

+ References

No definition available.

+ Details

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

- Definition

Individual loan balance is classified as nonaccrual status or troubled debt restructure.

+ References

No definition available.

+ Details

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

- Definition

This elements represents percentage of total loans.

+ References

No definition available.

+ Details

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

- Definition

The percentage of allowances on non performing loan losses.

+ References

No definition available.

+ Details

Name:	asrv_PercentageOfAllowanceForNonPerformingLoans
Namespace Prefix:	asrv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of allowances on total loan losses.

+ References

No definition available.

+ Details

Name:	asrv_PercentageOfAllowanceForTotalLoans
Namespace Prefix:	asrv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of other addition (reduction) in allowance reserve for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Amount, after recoveries, of loans and leases that have been written-off.

+ References

No definition available.

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_DoubtfulMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Allowance for Loan Losses (Details Textual) - USD ($)	3 Months Ended
Allowance for Loan Losses (Details Textual) - USD ($)	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individual loan balance is classified as nonaccrual status or troubled debt restructure	$ 100,000
Percentage Of Allowance For Non Performing Loans	460.00%		337.00%
Percentage Of Allowance For Total Loans	1.14%		1.15%
Allowance for Loan and Lease Losses, Adjustments, Net	$ 50,000	$ 225,000
Allowance for Loan and Lease Losses Write-offs, Net	$ 332,000	$ 77,000
Allowance For Loan And Lease Losses Write Off Percentage	0.15%	0.04%
Debt Instrument Non Performing Assets	$ 2,200,000
Percentage for Total Loans	0.25%
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold for individually evaluating loans	$ 250,000
Allowance for Loan and Lease Losses, Adjustments, Net	(316,000)	$ (24,000)
Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum individual loan balance requiring quarterly review	1,000,000
Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum individual loan balance requiring quarterly review	250,000
Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum individual loan balance requiring quarterly review	$ 100,000
Minimum [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum percent of portfolio to be reviewed	50.00%
Maximum [Member] \| Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum percent of portfolio to be reviewed	55.00%