Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2016
Document And Entity Information [Abstract]
Trading Symbol	ASB
Entity Registrant Name	ASSOCIATED BANC-CORP
Entity Central Index Key	0000007789
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
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			$ 3,831,497,000
Entity Common Stock, Shares Outstanding		151,688,740