Document and Entity Information (USD $)	9 Months Ended
	Sep. 30, 2012	Oct. 31, 2012	Jun. 30, 2012
Document And Entity Information [Abstract]
Entity Registrant Name	ASSOCIATED BANC-CORP
Entity Central Index Key	0000007789
Document Type	10-Q
Document Period End Date	Sep. 30, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,235,635,000
Entity Common Stock, Shares Outstanding		171,662,324