Parent Company Only Financial Information, Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Cash and due from banks	$ 446,558	$ 374,921
Investment securities available for sale, at fair value	4,680,226	4,967,414
Other assets	1,074,937	1,043,831
Total assets	29,139,315	27,711,835
LIABILITIES AND STOCKHOLDERS’ EQUITY
Commercial paper	101,688	67,978
Senior notes, at par	250,000	680,000
Subordinated notes, at par	250,000	250,000
Other Long-term Debt and Capitalized Costs	(3,393)	(4,061)
Total long-term funding	2,761,795	2,676,164
Accrued expenses and other liabilities	254,622	222,914
Total liabilities	26,048,003	24,774,589
Preferred equity	159,929	121,379
Common equity	1,630	1,642
Total stockholders’ equity	3,091,312	2,937,246	$ 2,800,251	$ 2,891,290
Total liabilities and stockholders’ equity	29,139,315	27,711,835
Associated Banc-Corp
ASSETS
Cash and due from banks	402,786	610,862
Investment securities available for sale, at fair value	14,389	61,847
Investment in subsidiaries	3,248,763	3,211,685
Other assets	61,242	70,595
Total assets	3,727,180	3,954,989
LIABILITIES AND STOCKHOLDERS’ EQUITY
Commercial paper	101,688	67,978
Senior notes, at par	250,000	680,000
Subordinated notes, at par	250,000	250,000
Other Long-term Debt and Capitalized Costs	(3,393)	(4,061)
Total long-term funding	496,607	925,939
Accrued expenses and other liabilities	37,573	23,826
Total liabilities	635,868	1,017,743
Preferred equity	159,929	121,379
Common equity	2,931,383	2,815,867
Total stockholders’ equity	3,091,312	2,937,246
Total liabilities and stockholders’ equity	$ 3,727,180	$ 3,954,989