Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2017

Regulatory Capital Requirements [Abstract]

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations

	Actual				For Capital Adequacy Purposes					To Be Well Capitalized Under Prompt Corrective Action Provisions (b)
	Amount		Ratio (a)		Amount		Ratio (a)			Amount		Ratio (a)
	($ in Thousands)
As of December 31 , 2017
Associated Banc-Corp
Total capital	$	2,848,851	13.22	%	$	1,723,557	≥	8.00	%
Tier 1 capital	2,331,245		10.82	%	1,292,668		≥	6.00	%
Common equity Tier 1 capital	2,171,508		10.08	%	969,501		≥	4.50	%
Leverage	2,331,245		8.02	%	1,162,929		≥	4.00	%
Associated Bank, N.A.
Total capital	$	2,625,945	12.24	%	$	1,716,910	≥	8.00	%	$	2,146,138	≥	10.00	%
Tier 1 capital	2,357,354		10.98	%	1,287,683		≥	6.00	%	1,716,910		≥	8.00	%
Common equity Tier 1 capital	2,157,354		10.05	%	965,762		≥	4.50	%	1,394,989		≥	6.50	%
Leverage	2,357,354		8.13	%	1,159,959		≥	4.00	%	1,449,448		≥	5.00	%
As of December 31 , 2016
Associated Banc-Corp
Total capital	$	2,706,760	12.68	%	$	1,707,276	≥	8.00	%
Tier 1 capital	2,191,798		10.27	%	1,280,457		≥	6.00	%
Common equity Tier 1 capital	2,032,587		9.52	%	960,343		≥	4.50	%
Leverage	2,191,798		7.83	%	1,119,685		≥	4.00	%
Associated Bank, N.A.
Total capital	$	2,565,062	12.07	%	$	1,700,737	≥	8.00	%	$	2,125,921	≥	10.00	%
Tier 1 capital	2,298,812		10.81	%	1,275,553		≥	6.00	%	1,700,737		≥	8.00	%
Common equity Tier 1 capital	2,098,812		9.87	%	956,664		≥	4.50	%	1,381,849		≥	6.50	%
Leverage	2,298,812		8.24	%	1,115,731		≥	4.00	%	1,394,663		≥	5.00	%

(a) When fully phased-in on January 1, 2019, the Basel III capital rules include a capital conservation buffer of 2.5% that is added on top of each of the minimum risk-based capital ratios noted above. Implementation began on January 1, 2016 at the 0.625% level and will increase each subsequent January 1, until it reaches 2.5% on January 1, 2019.

(b) Prompt corrective action provisions are not applicable at the bank holding company level.