Allowance for Loan Losses (Rollforward of the Allowance for Loan Losses by Portfolio Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	$ 9,623	$ 10,104
Charge-offs	(271)	(217)
Recoveries	87	222
Provision (Credit)	250
Balance at end of period	9,689	10,109
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	3,262	2,844
Charge-offs	(121)	(72)
Recoveries	6	50
Provision (Credit)	10	243
Balance at end of period	3,157	3,065
Commercial loans secured by real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	3,902	4,885
Charge-offs		(66)
Recoveries	42	153
Provision (Credit)	143	(310)
Balance at end of period	4,087	4,662
Real estate-mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	1,310	1,260
Charge-offs	(103)	(43)
Recoveries	30	14
Provision (Credit)	67	42
Balance at end of period	1,304	1,273
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	190	136
Charge-offs	(47)	(36)
Recoveries	9	5
Provision (Credit)	39	34
Balance at end of period	191	139
Allocation for general risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	959	979
Charge-offs
Recoveries
Provision (Credit)	(9)	(9)
Balance at end of period	$ 950	$ 970

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

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=35738203&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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

+ Details

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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

+ Details

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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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