Business Combinations - Acquisition-Related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Noninterest Expense [Abstract]
Compensation and employee benefits	$ 16,617	$ 12,579
Legal and professional	1,535	965
Data processing	1,354	845
Other	2,141	1,150
ATBancorp
Noninterest Expense [Abstract]
Compensation and employee benefits	0	10
Legal and professional	0	126
Data processing	44	5
Other	10	26
Total impact of acquisition-related costs to noninterest expense	$ 54	$ 167

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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The amount of expenses incurred in the period for information technology and data processing products and services.

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Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit.

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Amount of noninterest expense classified as other.

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A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.

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