Parent Company Only Financial Information, Statement of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
INCOME
Interest income on notes receivable	$ 659,538	$ 615,627	$ 598,582
Total income	(1,060,156)	(1,005,635)	(971,828)
EXPENSE
Income before income taxes	287,596	269,788	276,045
Income tax expense	87,322	81,487	85,536
Net income	200,274	188,301	190,509
Preferred stock dividends	(8,903)	(7,155)	(5,002)
Net income available to common equity	191,371	181,146	185,507
Associated Banc-Corp
INCOME
Dividends from subsidiaries	188,000	205,000	223,000
Interest income on notes receivable	0	0	1,264
Other income	4,669	8,441	9,713
Total income	(192,669)	(213,441)	(233,977)
EXPENSE
Interest expense on short and long-term funding	21,901	39,576	24,847
Other expense	4,289	4,684	776
Total expense	26,190	44,260	25,623
Income before income taxes	166,479	169,181	208,354
Income tax expense	3,468	(1,665)	(5,801)
Income before equity in undistributed net income (loss) of subsidiaries	163,011	170,846	214,155
Equity in undistributed net income (loss) of subsidiaries	37,263	17,455	(23,646)
Net income	200,274	188,301	190,509
Preferred stock dividends	8,903	7,155	5,002
Net income available to common equity	$ 191,371	$ 181,146	$ 185,507