Loan portfolio classified as performance and nonperformance.

No definition available.

Name:	asrv_LoanPortfolioClassifiedAsPerformanceAndNonperformanceAbstract
Namespace Prefix:	asrv_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ 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

Reference 2: 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

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

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of 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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: 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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

+ Details

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

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease.

+ References

Reference 1: 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

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

- Definition

Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn.

+ References

+ Details

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

- Definition

Amortized cost excluding accrued interest, of revolving financing receivable converted to term loan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated two years before current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Definition

Amount, excluding accrued interest, of writeoff of financing receivable originated in fiscal year before current fiscal year. Excludes net investment in lease.

+ References

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=asrv_ConsumerAndResidentialMortgagesPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_PerformingFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_NonperformingFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Allowance for Credit Losses - Loans - Residential and consumer portfolio (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Performing and non-performing outstanding balances of the residential and consumer portfolios
Total loans		$ 1,055,683		$ 1,055,683		$ 1,067,949
Current period gross charge-offs, Total	$ 2,800	7	$ 204	3,088	$ 620
Consumer and Residential mortgages
Performing and non-performing outstanding balances of the residential and consumer portfolios
2025/2024		13,077		13,077		24,353
2024/2023		23,207		23,207		26,700
2023/2022		24,070		24,070		26,843
2022/2021		23,839		23,839		65,145
2021/2020		60,645		60,645		44,402
Prior		81,377		81,377		43,466
Revolving Loans Amortized Cost Basis		57,934		57,934		54,148
Revolving Loans Converted to Term		37		37		664
Total loans		284,186		284,186		285,721
Current period gross charge-offs, 2025/2024				1		5
Current period gross charge-offs, 2024/2023				28		6
Current period gross charge-offs, 2023/2022				32		21
Current period gross charge-offs, 2022/2021				4		19
Current period gross charge-offs, 2021/2020						13
Current period gross charge-offs, Prior				61		143
Current period gross charge-offs, Total				126		207
Residential mortgages
Performing and non-performing outstanding balances of the residential and consumer portfolios
2025/2024		3,492		3,492		12,877
2024/2023		13,941		13,941		15,602
2023/2022		15,317		15,317		10,400
2022/2021		10,184		10,184		57,540
2021/2020		54,351		54,351		41,868
Prior		75,327		75,327		38,823
Total loans		172,612		172,612		177,110
Consumer
Performing and non-performing outstanding balances of the residential and consumer portfolios
2025/2024		9,585		9,585		11,476
2024/2023		9,266		9,266		11,098
2023/2022		8,753		8,753		16,443
2022/2021		13,655		13,655		7,605
2021/2020		6,294		6,294		2,534
Prior		6,050		6,050		4,643
Revolving Loans Amortized Cost Basis		57,934		57,934		54,148
Revolving Loans Converted to Term		37		37		664
Total loans		111,574		111,574		108,611
Current period gross charge-offs, 2025/2024				1		5
Current period gross charge-offs, 2024/2023				28		6
Current period gross charge-offs, 2023/2022				32		21
Current period gross charge-offs, 2022/2021				4		19
Current period gross charge-offs, 2021/2020						13
Current period gross charge-offs, Prior				61		143
Current period gross charge-offs, Total		7	$ 72	126	$ 196	207
Performing \| Consumer and Residential mortgages
Performing and non-performing outstanding balances of the residential and consumer portfolios
2025/2024		13,077		13,077		24,353
2024/2023		23,201		23,201		26,590
2023/2022		23,994		23,994		26,797
2022/2021		23,821		23,821		65,145
2021/2020		60,489		60,489		44,343
Prior		80,739		80,739		42,717
Revolving Loans Amortized Cost Basis		57,737		57,737		53,876
Revolving Loans Converted to Term		32		32		664
Total loans		283,090		283,090		284,485
Performing \| Residential mortgages
Performing and non-performing outstanding balances of the residential and consumer portfolios
2025/2024		3,492		3,492		12,877
2024/2023		13,941		13,941		15,602
2023/2022		15,317		15,317		10,400
2022/2021		10,184		10,184		57,540
2021/2020		54,195		54,195		41,868
Prior		75,027		75,027		38,418
Total loans		172,156		172,156		176,705
Performing \| Consumer
Performing and non-performing outstanding balances of the residential and consumer portfolios
2025/2024		9,585		9,585		11,476
2024/2023		9,260		9,260		10,988
2023/2022		8,677		8,677		16,397
2022/2021		13,637		13,637		7,605
2021/2020		6,294		6,294		2,475
Prior		5,712		5,712		4,299
Revolving Loans Amortized Cost Basis		57,737		57,737		53,876
Revolving Loans Converted to Term		32		32		664
Total loans		110,934		110,934		107,780
Non-performing \| Consumer and Residential mortgages
Performing and non-performing outstanding balances of the residential and consumer portfolios
2024/2023		6		6		110
2023/2022		76		76		46
2022/2021		18		18
2021/2020		156		156		59
Prior		638		638		749
Revolving Loans Amortized Cost Basis		197		197		272
Revolving Loans Converted to Term		5		5
Total loans		1,096		1,096		1,236
Non-performing \| Residential mortgages
Performing and non-performing outstanding balances of the residential and consumer portfolios
2021/2020		156		156
Prior		300		300		405
Total loans		456		456		405
Non-performing \| Consumer
Performing and non-performing outstanding balances of the residential and consumer portfolios
2024/2023		6		6		110
2023/2022		76		76		46
2022/2021		18		18
2021/2020						59
Prior		338		338		344
Revolving Loans Amortized Cost Basis		197		197		272
Revolving Loans Converted to Term		5		5
Total loans		$ 640		$ 640		$ 831