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Acquisitions - Schedule of Unaudited Pro Forma Revenue and Income (Details) - USD ($) $ / shares in Units, $ in Millions |  | 12 Months Ended
--- | --- | ---
Feb. 01, 2022 | Dec. 31, 2022 | Dec. 31, 2021
Business Acquisition [Line Items] |  |  |
Estimated useful lives of related deposits |  | 12 years |
Business Acquisition, Pro Forma Earnings Per Share, Basic |  | $ 3.28 | $ 2.24
Business Acquisition, Pro Forma Earnings Per Share, Diluted |  | $ 3.28 | $ 2.24
Great Western Bank |  |  |
Business Acquisition [Line Items] |  |  |
Business Acquisition, Pro Forma Revenue |  | $ 1,223.3 | $ 1,200.9
Business Acquisition, Pro Forma Net Income (Loss) |  | $ 351.6 | $ 243.3
Core Deposits Intangibles |  |  |
Business Acquisition [Line Items] |  |  |
Estimated useful lives of related deposits | 10 years | 10 years |

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- Definition The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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