Regulatory Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Associated Banc-Corp
Regulatory Capital [Abstract]
Total capital	$ 3,208,625	$ 3,216,575
Total Capital Actual Ratio	13.21%	13.49%
Total Capital for Capital Adequacy Purposes Amount	$ 1,943,711	$ 1,907,403
Total Capital for Adequacy Purposes Ratio	8.00%	8.00%
Tier 1 Capital Actual Amount	$ 2,736,776	$ 2,705,939
Tier 1 Capital Actual Ratio	11.26%	11.35%
Tier 1 Capital for Adequacy Purposes Amount	$ 1,457,783	$ 1,430,553
Tier 1 Capital for Adequacy Purposes Ratio	6.00%	6.00%
Common Equity Tier One Capital	$ 2,480,698	$ 2,449,721
Common Equity Tier One Capital to Risk Weighted Assets	10.21%	10.27%
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,093,337	$ 1,072,914
Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Tier 1 Leverage Capital Actual Amount	$ 2,736,776	$ 2,705,939
Tier 1 Leverage Capital Actual Ratio	8.83%	8.49%
Tier 1 Leverage Capital for Adequacy Purposes Amount	$ 1,239,431	$ 1,275,048
Tier 1 Leverage Capital for Adequacy Purposes Ratio	4.00%	4.00%
Associated Bank, N.A.
Regulatory Capital [Abstract]
Total capital	$ 2,892,650	$ 2,909,064
Total Capital Actual Ratio	11.95%	12.25%
Total Capital for Capital Adequacy Purposes Amount	$ 1,936,732	$ 1,900,536
Total Capital for Adequacy Purposes Ratio	8.00%	8.00%
Total Capital to be Well Capitalized Amount	$ 2,420,915	$ 2,375,671
Total Capital to be Well Capitalized Ratio	10.00%	10.00%
Tier 1 Capital Actual Amount	$ 2,669,372	$ 2,646,705
Tier 1 Capital Actual Ratio	11.03%	11.14%
Tier 1 Capital for Adequacy Purposes Amount	$ 1,452,549	$ 1,425,402
Tier 1 Capital for Adequacy Purposes Ratio	6.00%	6.00%
Tier 1 Capital To Be Well Capitalized Amount	$ 1,936,732	$ 1,900,536
Tier 1 Capital To Be Well Capitalized Ratio	8.00%	8.00%
Common Equity Tier One Capital	$ 2,469,578	$ 2,446,782
Common Equity Tier One Capital to Risk Weighted Assets	10.20%	10.30%
Common Equity Tier One Capital Required for Capital Adequacy	$ 1,089,412	$ 1,069,052
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	$ 1,573,595	$ 1,544,186
Tier 1 Equity Capital to be Well Capitalized Ratio	6.50%	6.50%
Tier 1 Leverage Capital Actual Amount	$ 2,669,372	$ 2,646,705
Tier 1 Leverage Capital Actual Ratio	8.63%	8.32%
Tier 1 Leverage Capital for Adequacy Purposes Amount	$ 1,236,565	$ 1,272,804
Tier 1 Leverage Capital for Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 Leverage Capital To Be Well Capitalized Amount	$ 1,545,706	$ 1,591,006
Tier 1 Leverage Capital To Be Well Capitalized Ratio	5.00%	5.00%

Common Equity Tier One Capital Required for Capital Adequacy to Risk Weighted Assets

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Common Equity Tier One Capital Required to be Well Capitalized to Risk Weighted Assets

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.

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Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as adequately capitalized under regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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