Name:	asb_AllowanceAttributableToFinancingReceivableAcquiredAndAccountedUnderModificationOfImpairedLoans
Namespace Prefix:	asb_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

This element represents the financing receivables that were acquired and accounted for under ASC 310-30.

No definition available.

Name:	asb_FinancingReceivableAcquiredAndAccountedUnderModificationOfImpairedLoans
Namespace Prefix:	asb_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Loans.

No definition available.

Name:	asb_LoansAbstract
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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

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

No definition available.

Name:	us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet
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- References

No definition available.

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract
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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward
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The balance of financing receivables that were collectively evaluated for impairment.

Name:	us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The balance of financing receivables that were individually evaluated for impairment.

Name:	us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Period Type:	instant

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Name:	us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of expense related to estimated loss from loan and lease transactions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Topic 942
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Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=asb_RealEstateConstructionPortFolioSegmentMember
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