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Acquisition of a Business - Summary of Estimated Fair Values of Assets and Liabilities Assumed as of Acquisition Date (Parenthetical) (Details) - $ / shares | Apr. 30, 2019 | May 31, 2018
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Oak Park River Forest Bankshares, Inc. |  |
Business Acquisition [Line Items] |  |
Stock issued (in shares) | 1,464,558 |
Stock issued (in dollars per share) | $ 20.02 |
First Evanston Bancorp, Inc. |  |
Business Acquisition [Line Items] |  |
Stock issued (in shares) |  | 6,682,850
Stock issued (in dollars per share) |  | $ 21.62

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- Definition Number of shares of equity interests issued or issuable to acquire entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
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