Name:	asb_Heldtomaturitysecuritiescontinuousunrealizedlossposition12monthsorlongeraccumulatedloss
Namespace Prefix:	asb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

This item represents the excess of amortized cost basis over fair value of securities in a loss position and which are categorized as held-to-maturity.

No definition available.

Name:	asb_Heldtomaturitysecuritiescontinuousunrealizedlosspositionaccumulatedloss
Namespace Prefix:	asb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity that have been in a continuous loss position for less than twelve months.

No definition available.

Name:	asb_Heldtomaturitysecuritiescontinuousunrealizedlosspositionlessthan12monthsaccumulatedloss
Namespace Prefix:	asb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

This item represents the fair value of securities categorized as held-to-maturity which are in an unrealized loss position.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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

This item represents the fair value of securities categorized as held-to-maturity that have been in a continuous unrealized loss position for less than twelve months.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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

This item represents the fair value of securities categorized as held-to-maturity securities that have been in a continuous unrealized loss position for twelve months or longer.

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

Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

Name:	us-gaap_HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

Name:	asb_LengthoftimeheldtomaturitysecuritiesareincontinuousunrealizedlosspositionaxisAxis=asb_HeldtomaturitysecuritiesinunrealizedlosspositionsqualitativedisclosurenumberofpositionsgreaterthanorequaltooneyearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	asb_LengthoftimeheldtomaturitysecuritiesareincontinuousunrealizedlosspositionaxisAxis=asb_HeldtomaturitysecuritiesinunrealizedlosspositionsqualitativedisclosurenumberofpositionslessthanoneyearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: