| Document and Entity Information | Oct. 02, 2020 |
| Details | |
| Registrant CIK | 0000007789 |
| Registrant Name | Associated Banc-Corp |
| SEC Form | 8-K |
| Period End date | Oct. 2, 2020 |
| Trading Symbol | ASB |
| Trading Exchange | NYSE |
| Tax Identification Number (TIN) | 39-1098068 |
| Emerging Growth Company | false |
| Entity Incorporation, State or Country Code | WI |
| Entity File Number | 001-31343 |
| Entity Address, Address Line One | 433 Main Street |
| Entity Address, City or Town | Green Bay |
| Entity Address, State or Province | WI |
| Entity Address, Postal Zip Code | 54301 |
| City Area Code | 920 |
| Local Phone Number | 491-7500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, Par Value $0.01 per share |
| Amendment Flag | false |
