Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 26, 2019
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2019
Document Transition Report	false
Entity File Number	001-31343
Entity Registrant Name	Associated Banc-Corp
Entity Incorporation, State or Country Code	WI
Entity Address, Address Line One	433 Main Street
Entity Address, City or Town	Green Bay,
Entity Address, State or Province	WI
Entity Tax Identification Number	39-1098068
Entity Address, Postal Zip Code	54301
City Area Code	920
Local Phone Number	491-7500
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		162,166,503
Entity Central Index Key	0000007789
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
The New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	ASB
Security Exchange Name	NYSE
Series C Preferred Stock | The New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shrs, each representing 1/40th intrst in a shr of 6.125% Non-Cum. Perp Pref Stock, Srs C
Trading Symbol	ASB PrC
Security Exchange Name	NYSE
Series D Preferred Stock | The New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shrs, each representing 1/40th intrst in a shr of 5.375% Non-Cum. Perp Pref Stock, Srs D
Trading Symbol	ASB PrD
Security Exchange Name	NYSE
Series E Preferred Stock | The New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shrs, each representing 1/40th intrst in a shr of 5.875% Non-Cum. Perp Pref Stock, Srs E
Trading Symbol	ASB PrE
Security Exchange Name	NYSE