Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 25, 2018
Document And Entity Information [Abstract]
Trading Symbol	ASB
Entity Registrant Name	ASSOCIATED BANC-CORP
Entity Central Index Key	0000007789
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
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 Common Stock, Shares Outstanding		172,093,888