Regulatory Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Associated Banc-Corp
Regulatory Capital [Abstract]
Total capital	$ 3,570,026	$ 3,632,807
Total Capital Actual Ratio	13.10%	14.02%
Total Capital for Capital Adequacy Purposes Amount	$ 2,179,419	$ 2,072,273
Total Capital for Adequacy Purposes Ratio	8.00%	8.00%
Tier 1 Capital Actual Amount	$ 3,001,074	$ 3,058,809
Tier 1 Capital Actual Ratio	11.02%	11.81%
Tier 1 Capital for Adequacy Purposes Amount	$ 1,634,564	$ 1,554,205
Tier 1 Capital for Adequacy Purposes Ratio	6.00%	6.00%
Common Equity Tier One Capital	$ 2,808,289	$ 2,706,010
Common Equity Tier One Capital to Risk Weighted Assets	10.31%	10.45%
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,225,923	$ 1,165,654
Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Tier 1 Leverage Capital Actual Amount	$ 3,001,074	$ 3,058,809
Tier 1 Leverage Capital Actual Ratio	8.83%	9.37%
Tier 1 Leverage Capital for Adequacy Purposes Amount	$ 1,359,299	$ 1,305,604
Tier 1 Leverage Capital for Adequacy Purposes Ratio	4.00%	4.00%
Associated Bank, N.A.
Regulatory Capital [Abstract]
Total capital	$ 3,243,672	$ 3,295,823
Total Capital Actual Ratio	11.93%	12.74%
Total Capital for Capital Adequacy Purposes Amount	$ 2,175,689	$ 2,068,801
Total Capital for Adequacy Purposes Ratio	8.00%	8.00%
Total Capital to be Well Capitalized Amount	$ 2,719,611	$ 2,586,002
Total Capital to be Well Capitalized Ratio	10.00%	10.00%
Tier 1 Capital Actual Amount	$ 2,923,881	$ 2,971,234
Tier 1 Capital Actual Ratio	10.75%	11.49%
Tier 1 Capital for Adequacy Purposes Amount	$ 1,631,766	$ 1,551,601
Tier 1 Capital for Adequacy Purposes Ratio	6.00%	6.00%
Tier 1 Capital To Be Well Capitalized Amount	$ 2,175,689	$ 2,068,801
Tier 1 Capital To Be Well Capitalized Ratio	8.00%	8.00%
Common Equity Tier One Capital	$ 2,923,881	$ 2,971,234
Common Equity Tier One Capital to Risk Weighted Assets	10.75%	11.49%
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,223,825	$ 1,163,701
Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Tier 1 Equity Capital to be Well Capitalized Amount	$ 1,767,747	$ 1,680,901
Tier 1 Equity Capital to be Well Capitalized Ratio	6.50%	6.50%
Tier 1 Leverage Capital Actual Amount	$ 2,923,881	$ 2,971,234
Tier 1 Leverage Capital Actual Ratio	8.61%	9.11%
Tier 1 Leverage Capital for Adequacy Purposes Amount	$ 1,358,041	$ 1,304,448
Tier 1 Leverage Capital for Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 Leverage Capital To Be Well Capitalized Amount	$ 1,697,551	$ 1,630,560
Tier 1 Leverage Capital To Be Well Capitalized Ratio	5.00%	5.00%