Fair Value Measurements (Details Textuals)	3 Months Ended
Mar. 31, 2021
Fair Value Measurements (Textuals) [Abstract]
Fair Value Inputs Closing Ratio	89.00%

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:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration