Fair Value Measurements (Details Textuals)	9 Months Ended
Sep. 30, 2018
Fair Value of Assets and Liabilities [Line Items]
Closing ratio	86.00%

Represents the percentage of loans currently in a lock position which management estimates will ultimately close.

No definition available.

Name:	asb_FairValueInputsClosingRatio
Namespace Prefix:	asb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration