Document and Entity Information - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2025	Jul. 25, 2025
Entity Information [Line Items]
Document Type	10-Q	10-Q
Document Quarterly Report		true
Document Period End Date		Jun. 30, 2025
Document Transition Report		false
Entity File Number		001-31343
Entity Registrant Name	Associated Banc-Corp	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			165,848,030
Entity Central Index Key		0000007789
Amendment Flag		false
Document Fiscal Year Focus		2025
Document Fiscal Period Focus		Q2
Current Fiscal Year End Date		--12-31
Document Information [Line Items]
Amendment Flag		false
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
The New York Stock Exchange | Two Thousand Twenty Three Subordinated Notes [Member]
Entity Information [Line Items]
Title of 12(b) Security		6.625% Fixed-Rate Reset Subordinated Notes due 2033
Trading Symbol		ASBA
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
Series F 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 5.625% Non-Cum. Perp Pref Stock, Srs F
Trading Symbol		ASB PrF
Security Exchange Name		NYSE